16 files declare their use of TermInterface in Drupal 8

DeleteForm.php in core/modules/forum/src/Form/DeleteForm.php

EntityReferenceItemTest.php in core/modules/field/tests/src/Kernel/EntityReference/EntityReferenceItemTest.php

ForumController.php in core/modules/forum/src/Controller/ForumController.php

MigrateTaxonomyTermTest.php in core/modules/taxonomy/tests/src/Kernel/Migrate/d7/MigrateTaxonomyTermTest.php

MigrateTaxonomyTermTranslationTest.php in core/modules/content_translation/tests/src/Kernel/Migrate/d6/MigrateTaxonomyTermTranslationTest.php

MigrateTaxonomyTermTranslationTest.php in core/modules/taxonomy/tests/src/Kernel/Migrate/d7/MigrateTaxonomyTermTranslationTest.php

MigrateTermLocalizedTranslationTest.php in core/modules/taxonomy/tests/src/Kernel/Migrate/d6/MigrateTermLocalizedTranslationTest.php

MigrateTermLocalizedTranslationTest.php in core/modules/taxonomy/tests/src/Kernel/Migrate/d7/MigrateTermLocalizedTranslationTest.php

taxonomy.module in core/modules/taxonomy/taxonomy.module

Enables the organization of content into categories.

TaxonomyController.php in core/modules/taxonomy/src/Controller/TaxonomyController.php

TaxonomyLegacyTest.php in core/modules/taxonomy/tests/src/Kernel/TaxonomyLegacyTest.php

TaxonomyRelationshipTest.php in core/modules/taxonomy/tests/src/Functional/Views/TaxonomyRelationshipTest.php

Term.php in core/modules/taxonomy/src/Entity/Term.php

TermAccessTest.php in core/modules/taxonomy/tests/src/Functional/TermAccessTest.php

TermParentsTest.php in core/modules/taxonomy/tests/src/Functional/TermParentsTest.php

Tid.php in core/modules/taxonomy/src/Plugin/views/argument_default/Tid.php