Explanation
Expresses that just doing something is not enough or will not suffice.
Formation
Verb-dictionary form + ではすまない / い-Adjective + ではすまない / な-Adjective + ではすまない / Noun + ではすまない
Detailed explanation
The grammar point ～ではすまない is used when the speaker strongly feels that an action or situation alone is not sufficient or acceptable, implying that more serious measures are needed or that the consequences are more severe.
Examples
Tada ayamaru dewa sumanai. Nanika koudou o toranakereba naranai.
Just apologizing will not suffice. Some action needs to be taken.
Kono mondai wa giron dake dewa sumanai. Gutaiteki na keikaku ga hitsuyou da.
This problem won't be solved with just discussions. A concrete plan is needed.
Kare no shippai wa chuui dake dewa sumanai. Kare wa sono sekinin o toru beki da.
His failure won't be resolved with just a warning. He should take responsibility.
Kono shippai wa kane dake dewa sumanai. Shinrai o torimodosu tame, magokoro de shazai suru beki da.
This mistake cannot be settled with money alone. To regain trust, an earnest apology is needed.
Practice
Grammar content sourced from hanabira.org.