[with infinitive]having the power, skill, means, or opportunity to do something 有能力(或技能、手段、机会)的 he was able to read Greek at the age of eight. 他八岁时就能读希腊文了。 they would never be able to afford such a big house. 他们永远买不起那么大的房子。
having considerable skill, proficiency, or intelligence 聪明能干的,有才干的 the dancers were technically very able. 这些舞蹈演员的演技十分出众。
语源
late Middle English (also in the sense 'easy to use, suitable'): from Old French hable, from Latin habilis 'handy', from habere 'to hold'