An onomatopoeia for loud, clangorous sounds (e.g. bells); often used with the particle 'と'.
裏の工事現場からドラムがじゃんじゃんと響いてくる。
Drums are resoundingly banging from the construction site next door.
祭りの太鼓が朝からじゃんじゃん鳴っている。
The festival drums have been going bang, bang since morning.
銭湯の釣り鐘がじゃんじゃんと鳴らされた。
The bathhouse bell was rung with a clang.
An adverb meaning continuously or in large amounts; doing something one after another or freely/plentifully.
注文がじゃんじゃん入って、店がてんてこ舞いだ。
Orders keep coming in one after another, and the shop is swamped.
景気がよくてお金をじゃんじゃん使ってしまった。
Business was good and I ended up spending money freely.
新入社員がじゃんじゃん提案を出している。
The new employees are putting forward proposals one after another.