• extentions,
• exention,
• exetention,
• wxtention,
• sxtention,
• dxtention,
• rxtention,
• 4xtention,
• 3xtention,
• eztention,
• ectention,
• estention,
• exrention,
• exfention,
• exgention,
• exyention,
• extentin,
• exteention,
• Extentional,
• extentioned

• extend,
• exodontics,
• extend to,
• extendable,
• extension,
• extendible,
• extensile,
• extended,
• extensive,
• excitement,
• extenuate,
• extenuation,
• extenuating,
• extent,
• extensible,
• exodontia,
• exodontic,
• extensively,
• extensor,
• exodontist,
• extensional,
• extant.

The adjective form of the word "extension" is "extended".

The plural form of the word "extension" is "extensions"

The singular form of the word "extension" is "extension"