As a Noun: 1. A combination of a natural and acquired ability (through education, experience or training) that enables you to do something well. English = skill, competence, proficiency. Informal English = know-how. 2. Special skill or knowledge. English = expertise. As a Verb or Adjective: 1. To have a combination of a natural and acquired ability (through education, experience or training) that enables you to do something well. English = (be) skilled, (be) competent, (be) proficient. Informal English = have the know-how. 2. To have special skill or knowledge. English = (be) expert, have expertise.