To Accumulate
To Get Piled Up
intransitive verb, godan verb
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means accumulate and the verb version is to accumulate.
If something accumulates, you can start with one, but you need at least two (つ) things to say it has accumulated. If you don't, then there's nothing accumulating at all.
雪はふるんですが、あまり積もることはないです。
It snows, but it doesn’t usually accumulate much.
年末に積もりに積もったホコリを全部そうじするつもりです。
I plan to clean up all the dust that piled up throughout the year at the end of the year.
「ちりも積もれば山となる」って言うし、毎日コツコツ頑張るよ！
They say "little by little, dust becomes a mountain," so I'll keep working hard every day!
長年積もりに積もった不満が、一気にあふれ出しちゃったんです。
The frustration that had built up over the years suddenly overflowed all at once.