ability的同义词是capacity，反义词是inability。
ability释义：
n.能力，能够；才能，技能，本领。
例句：
He completed the job to the best of his ability.
capacity释义：
n.容量；才能；职责；生产能力；载客量。
adj.座无虚席的。
例句：
The company has the capacity to build 1,500 trucks a year.
inability释义：
n.无能，无力；无才能；无能为力。
例句：
Some families go without medical treatment because of their inability to pay.
