Explanation
Expressing that something 'is not'; 'it's not like...'. Colloquial/masculine form of ではあるまいし.
Formation
Noun or Na-Adjective + じゃあるまいし
Detailed explanation
The phrase 「Noun (or Na-Adjective) + じゃあるまいし」 is a somewhat casual, sometimes masculine-sounding expression meaning 'it's not like...', 'it's not as if...', or 'there's no need to...' in certain contexts. It dismisses the idea that the noun or adjective is the reason or cause for something.
Examples
Kare wa kodomo ja aru mai shi, sono mondai o shikkari to kaiketsu suru beki da.
He’s not a child, so he should solve that problem properly.
Isogu hitsuyou wa nai, jikan ja aru mai shi.
We don’t need to hurry; it’s not like we’re short of time.
Kantoku ja aru mai shi, shiai no kekka ni tsuite shinpai suru na.
You’re not the coach, so don’t worry about the game results.
Ame ja aru mai shi, sono mama nomikonde mo daijoubu da yo.
It’s not candy, so it’s okay to just swallow it.
Practice
Grammar content sourced from hanabira.org.