adverb, adverb taking the 'to' particle
stifled laughter; chuckling quietly
Describes a low, suppressed laugh, often with the mouth closed or behind one's hand. Common in phrases like くつくつ笑う.
彼は漫画を読みながらくつくつ笑っていた。
He was chuckling quietly while reading the manga.
adverb, adverb taking the 'to' particle
simmering; bubbling gently
Describes the sound or state of a pot simmering with small bubbles. Often used with 煮る or 煮える.
鍋がくつくつと煮立っている。
The pot is simmering gently.