noun
middle-aged band; dad band
A band whose members are mostly middle-aged or older, often amateur. The term carries a casual, sometimes self-deprecating tone.
週末はオヤジバンドの練習がある。
I have dad band practice on the weekend.
あのオヤジバンド、けっこう上手いよね。
That middle-aged band is pretty good, isn't it?
Means 'father' or 'middle-aged man'. オヤジバンド specifically refers to a band made up of such men.
Compound of オヤジ (oyaji, 'middle-aged man') and バンド (bando, 'band'). The exact origin is uncertain, but it likely emerged in colloquial Japanese to describe amateur bands formed by older men.