To Be Negligent
To Neglect, To Shirk
transitive verb, godan verb
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. You learned the kanji means "lazy," but it can also mean neglect, so the verb means to be negligent or to neglect something.
怠る is a relatively formal word for failing to carry out a responsibility, either on purpose or due to forgetfulness or negligence. You'll see it in contexts like 義務を怠る (to neglect one's duty) or 注意を怠る (to fail to exercise caution).
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 this kanji, so here's a mnemonic to help you:
You have a bad tendency to be negligent with paying people back, so you owe quarters (おこた) to pretty much everyone you know. You owe quarters to your coworker for spotting you at the vending machine yesterday, and you owe quarters to your friend for all those games of air hockey at the arcade last weekend. Stop being so negligent with your debts!
この失敗は確認を怠った私の責任です。
I am responsible for this failure of neglecting to check it.