깜빡하다

깜빡하다 (kkampak-hada) is a verb that means “to forget momentarily” or “to slip one’s mind.” 깜빡 imitates a sound, which represents blinking or flickering—just like how a thought can disappear in an instant.

Example Sentences:

깜빡하고 지갑을 안 가져왔어! → “I totally forgot to bring my wallet!”
약속을 깜빡했어요. 미안해요! → “I completely forgot about our appointment. Sorry!”
숙제를 깜빡해서 선생님께 혼났어. → “I forgot my homework and got scolded by the teacher.”
깜빡하고 전화 안 했어. → “I totally forgot to call.”
열쇠를 깜빡하고 안 가져왔어요. → “I forgot to bring my keys.”

Another casual word is 까먹다 (kkameokda), which also means “to forget,” but in a more slangy and informal way.