pref. 不, 缺少, 无
【医】 不, 无, 缺; 离
英汉词典

a-的短语、例句：

a- pref 前缀 1 (with ns, adjs and advs 与名词, 形容词, 副词结合) not; without 不; 无; 非: atheist
atypical * asexually. =>Usage at un- 用法见un-. 2 (with vs forming adjs 与动词结合构成形容词) in the state or process of 处於...状态或过程中: awake
asleep * ablaze * adrift.