〜たものではない ta mono dewa nai
〜たものではない（ta mono dewa nai）means “can't possibly ...; not something one can ...”. Attaches to the た-form of a verb — typically the potential form — to express that something is so bad/extreme that one simply cannot do it. Formation: V（可能形）た＋ものではない（口语 〜たもんじゃない）。常与「とても」呼应
can't possibly ...; not something one can ...
N2Formation
V（可能形）た＋ものではない（口语 〜たもんじゃない）。常与「とても」呼应
Explanation
Attaches to the た-form of a verb — typically the potential form — to express that something is so bad/extreme that one simply cannot do it. The speaker strongly rejects the act as unbearable. Equivalent to 'totemo ...(rare)nai' (can't possibly do it). Almost always used with the potential: 食べられたものではない (can't possibly eat it), 聞けたものではない (can't bear to listen).
Examples
Note
Different from 〜たものだ (reminiscence). Here it means strong impossibility/rejection and normally takes the potential form (食べられた, 聞けた). The colloquial form is 〜たもんじゃない.
FAQ
〜たものではない — what does it mean and how is it used?
can't possibly ...; not something one can .... Attaches to the た-form of a verb — typically the potential form — to express that something is so bad/extreme that one simply cannot do it. The speaker strongly rejects the act as unbearable. Equivalent to 'totemo ...(rare)nai' (can't possibly do it). Almost always used with the potential: 食べられたものではない (can't possibly eat it), 聞けたものではない (can't bear to listen).
〜たものではない — how do you form it?
V（可能形）た＋ものではない（口语 〜たもんじゃない）。常与「とても」呼应
〜たものではない — any usage notes?
Different from 〜たものだ (reminiscence). Here it means strong impossibility/rejection and normally takes the potential form (食べられた, 聞けた). The colloquial form is 〜たもんじゃない.