To Spill Something, To Drop Something, To Shed Tears
transitive verb, godan verb
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means zero, but the verb vocab version means to spill something or to drop something. Think of it this way, if you spill something, eventually it will reach zero.
こぼす
Imagine you're co-boiling (こぼ) water with someone. With the two of you co-boiling, the water is boiling pretty hard. Watch out, though — you're about to spill the hot water everywhere!
「あんた、今カーペットに珈琲を零したでしょう？」「しまった!ごめん!」「ごめんで済んだら警察はいらないわよ！」
"Did you just spill coffee on the carpet?" "Oh no! Sorry." "If sorry fixed everything, we wouldn’t need the police!"