does not seem; unlikely; improbable
Attaches to the stem of adjectives and verbs to express a negative conjecture: 'it doesn't look like...', 'it seems not...'. Equivalent to 〜そうにない.
明日は雨が降らなさそうだ。
It doesn't look like it will rain tomorrow.
This problem doesn't seem easy.
He had a face that said he probably couldn't come.
Derived from the negative form of the auxiliary そうだ (〜そう) combined with ない, with an epenthetic さ inserted for euphony.