diff --git a/lib/Server.js b/lib/Server.js
index 7ef6706ea7..870e8c65ea 100644
--- a/lib/Server.js
+++ b/lib/Server.js
@@ -504,7 +504,7 @@ class Server {
     }
 
     if (this.options.https) {
-      for (const property of ['ca', 'pfx', 'key', 'cert']) {
+      for (const property of ['cacert', 'pfx', 'key', 'cert']) {
         const value = this.options.https[property];
         const isBuffer = value instanceof Buffer;
 
diff --git a/lib/options.json b/lib/options.json
index 461462fad3..bc0b3ae5fe 100644
--- a/lib/options.json
+++ b/lib/options.json
@@ -309,7 +309,7 @@
             "requestCert": {
               "type": "boolean"
             },
-            "ca": {
+            "cacert": {
               "anyOf": [
                 {
                   "type": "string"
diff --git a/test/__snapshots__/validate-options.test.js.snap.webpack4 b/test/__snapshots__/validate-options.test.js.snap.webpack4
index 3e050e0408..ee5bfc7c7a 100644
--- a/test/__snapshots__/validate-options.test.js.snap.webpack4
+++ b/test/__snapshots__/validate-options.test.js.snap.webpack4
@@ -178,18 +178,18 @@ exports[`options validate should throw an error on the "http2" option with '' va
 exports[`options validate should throw an error on the "https" option with '' value 1`] = `
 "ValidationError: Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.https should be one of these:
-   boolean | object { passphrase?, requestCert?, ca?, key?, pfx?, cert? }
+   boolean | object { passphrase?, requestCert?, cacert?, key?, pfx?, cert? }
    -> By default, dev-server will be served over HTTP. It can optionally be served over HTTP/2 with HTTPS. https://webpack.js.org/configuration/dev-server/#devserverhttps
    Details:
     * configuration.https should be a boolean.
     * configuration.https should be an object:
-      object { passphrase?, requestCert?, ca?, key?, pfx?, cert? }"
+      object { passphrase?, requestCert?, cacert?, key?, pfx?, cert? }"
 `;
 
 exports[`options validate should throw an error on the "https" option with '{"foo":"bar"}' value 1`] = `
 "ValidationError: Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.https has an unknown property 'foo'. These properties are valid:
-   object { passphrase?, requestCert?, ca?, key?, pfx?, cert? }"
+   object { passphrase?, requestCert?, cacert?, key?, pfx?, cert? }"
 `;
 
 exports[`options validate should throw an error on the "onAfterSetupMiddleware" option with 'false' value 1`] = `
diff --git a/test/__snapshots__/validate-options.test.js.snap.webpack5 b/test/__snapshots__/validate-options.test.js.snap.webpack5
index 3e050e0408..ee5bfc7c7a 100644
--- a/test/__snapshots__/validate-options.test.js.snap.webpack5
+++ b/test/__snapshots__/validate-options.test.js.snap.webpack5
@@ -178,18 +178,18 @@ exports[`options validate should throw an error on the "http2" option with '' va
 exports[`options validate should throw an error on the "https" option with '' value 1`] = `
 "ValidationError: Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.https should be one of these:
-   boolean | object { passphrase?, requestCert?, ca?, key?, pfx?, cert? }
+   boolean | object { passphrase?, requestCert?, cacert?, key?, pfx?, cert? }
    -> By default, dev-server will be served over HTTP. It can optionally be served over HTTP/2 with HTTPS. https://webpack.js.org/configuration/dev-server/#devserverhttps
    Details:
     * configuration.https should be a boolean.
     * configuration.https should be an object:
-      object { passphrase?, requestCert?, ca?, key?, pfx?, cert? }"
+      object { passphrase?, requestCert?, cacert?, key?, pfx?, cert? }"
 `;
 
 exports[`options validate should throw an error on the "https" option with '{"foo":"bar"}' value 1`] = `
 "ValidationError: Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.https has an unknown property 'foo'. These properties are valid:
-   object { passphrase?, requestCert?, ca?, key?, pfx?, cert? }"
+   object { passphrase?, requestCert?, cacert?, key?, pfx?, cert? }"
 `;
 
 exports[`options validate should throw an error on the "onAfterSetupMiddleware" option with 'false' value 1`] = `
diff --git a/test/server/https-option.test.js b/test/server/https-option.test.js
index 0e206ccd62..887aaba191 100644
--- a/test/server/https-option.test.js
+++ b/test/server/https-option.test.js
@@ -45,7 +45,7 @@ describe('https option', () => {
     afterAll(testServer.close);
   });
 
-  describe('as an object when ca, pfx, key and cert are buffer', () => {
+  describe('as an object when cacert, pfx, key and cert are buffer', () => {
     beforeAll((done) => {
       server = testServer.start(
         config,
@@ -55,7 +55,9 @@ describe('https option', () => {
             watch: false,
           },
           https: {
-            ca: fs.readFileSync(path.join(httpsCertificateDirectory, 'ca.pem')),
+            cacert: fs.readFileSync(
+              path.join(httpsCertificateDirectory, 'ca.pem')
+            ),
             pfx: fs.readFileSync(
               path.join(httpsCertificateDirectory, 'server.pfx')
             ),
@@ -79,14 +81,14 @@ describe('https option', () => {
     });
   });
 
-  describe('as an object when ca, pfx, key and cert are paths', () => {
+  describe('as an object when cacert, pfx, key and cert are paths', () => {
     beforeAll((done) => {
       server = testServer.start(
         config,
         {
           static: contentBasePublic,
           https: {
-            ca: path.join(httpsCertificateDirectory, 'ca.pem'),
+            cacert: path.join(httpsCertificateDirectory, 'ca.pem'),
             pfx: path.join(httpsCertificateDirectory, 'server.pfx'),
             key: path.join(httpsCertificateDirectory, 'server.key'),
             cert: path.join(httpsCertificateDirectory, 'server.crt'),
@@ -104,7 +106,7 @@ describe('https option', () => {
     });
   });
 
-  describe('as an object when ca, pfx, key and cert are symlinks', () => {
+  describe('as an object when cacert, pfx, key and cert are symlinks', () => {
     if (skipTestOnWindows('Symlinks are not supported on Windows')) {
       return;
     }
@@ -118,7 +120,7 @@ describe('https option', () => {
             watch: false,
           },
           https: {
-            ca: path.join(httpsCertificateDirectory, 'ca-symlink.pem'),
+            cacert: path.join(httpsCertificateDirectory, 'ca-symlink.pem'),
             pfx: path.join(httpsCertificateDirectory, 'server-symlink.pfx'),
             key: path.join(httpsCertificateDirectory, 'server-symlink.key'),
             cert: path.join(httpsCertificateDirectory, 'server-symlink.crt'),
@@ -138,7 +140,7 @@ describe('https option', () => {
     afterAll(testServer.close);
   });
 
-  describe('as an object when ca, pfx, key and cert are raw strings', () => {
+  describe('as an object when cacert, pfx, key and cert are raw strings', () => {
     beforeAll((done) => {
       server = testServer.start(
         config,
@@ -148,7 +150,7 @@ describe('https option', () => {
             watch: false,
           },
           https: {
-            ca: fs
+            cacert: fs
               .readFileSync(path.join(httpsCertificateDirectory, 'ca.pem'))
               .toString(),
             // pfx can't be string because it is binary format
@@ -186,7 +188,9 @@ describe('https option', () => {
           },
           https: {
             requestCert: true,
-            ca: fs.readFileSync(path.join(httpsCertificateDirectory, 'ca.pem')),
+            cacert: fs.readFileSync(
+              path.join(httpsCertificateDirectory, 'ca.pem')
+            ),
             pfx: fs.readFileSync(
               path.join(httpsCertificateDirectory, 'server.pfx')
             ),
diff --git a/test/validate-options.test.js b/test/validate-options.test.js
index eaabf2c05f..ee867d3968 100644
--- a/test/validate-options.test.js
+++ b/test/validate-options.test.js
@@ -180,7 +180,7 @@ const tests = {
       false,
       true,
       {
-        ca: join(httpsCertificateDirectory, 'ca.pem'),
+        cacert: join(httpsCertificateDirectory, 'ca.pem'),
         key: join(httpsCertificateDirectory, 'server.key'),
         pfx: join(httpsCertificateDirectory, 'server.pfx'),
         cert: join(httpsCertificateDirectory, 'server.crt'),
@@ -188,7 +188,7 @@ const tests = {
         passphrase: 'webpack-dev-server',
       },
       {
-        ca: readFileSync(join(httpsCertificateDirectory, 'ca.pem')),
+        cacert: readFileSync(join(httpsCertificateDirectory, 'ca.pem')),
         pfx: readFileSync(join(httpsCertificateDirectory, 'server.pfx')),
         key: readFileSync(join(httpsCertificateDirectory, 'server.key')),
         cert: readFileSync(join(httpsCertificateDirectory, 'server.crt')),