To Spend, To Expend, To Waste, To Consume
transitive verb, godan verb
Turn expense into a verb and you get to spend or to expend. Or, in some cases, to waste. In addition to spending money, 費やす can be used to refer to spending other resources like time, effort, energy, and emotions.
ついやす
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with the kanji, so here's a mnemonic to help you: Just as you're about to spend some money, a familiar sound comes from inside your wallet: "TWEET (つい)!" It's the little bird that lives inside your wallet and angrily tweets at you whenever you're about to waste money on something you don't need. Maybe you should listen to the bird tweeting from inside your wallet a little more.
勉強に時間を費やすのはとても良いことです。
Dedicating time to studying is a very good thing.
ムダな時間と労力を費やさないよう、気をつけています。
I'm trying to be careful not to waste time and effort.
男は、生活費のほとんどをパチンコに費やしてしまった。
The man spent most of his living expenses on pachinko.