also: なくちゃ
Used after the negative stem of a verb (ない-form minus ない) to mean 'without doing' or 'if not'. Often part of a conditional or negative obligation pattern.
朝ごはんを食べなくては、元気が出ない。
If I don't eat breakfast, I won't have any energy.
彼に会わなくては、何も始まらない。
Nothing will start unless I meet him.
宿題をやらなくては。
I must do my homework.
Colloquial contraction of なくては, common in casual speech.
Kanji spelling is uncommon; the kana form is strongly preferred.
Kanji spelling of the colloquial contraction; very rare.
From the negative continuative form なく (from ない) + particle て + topic particle は. The contracted form なくちゃ derives from なくては via regular sound change.