Adjective:

1. sung without instrumental accompaniment;

   "they sang an a cappella Mass"
   

Adverb:

1. without musical accompaniment;

   "they performed a cappella"
   

Ajawi阿贾维aart.一(个)；每一(个)；任一(个)n.英语字母表的第一个字母；学业成绩得优者；表示“最好”的符号a block of shares一大宗股份a boiler plate.锅炉板A crisis of faith信仰危机a payment voucher付款凭证a chief of police警长.a pair of pyjamas一套睡衣a leggy dancer.双腿修长的舞女a butcher's blocka dashing coat.时髦的上衣。a maternity nurse产科护士

1. They performed a cappella.
   他们的表演不用乐器伴奏。