This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

v. Simple past tense and past participle of remain.

"Whatever his actual thoughts concerning the Uzachile, his expression remained controlled."

unexhausted   

surplus    residual    residuary    behind    residuous    remanent    odd    balance    rest    surviving   

remain   

abstaining    ascertaining    attaining    campaigning    caning    chaining    complaining    constraining    containing    deigning