1N-COUNT [usually singular](大学的)假期,寒暑假 A vac is a period of the year when universities and colleges are officially closed. Vac is an abbreviation for 'vacation'. (大学的)假期,寒暑假 [British, informal]
...the summer vac.
暑假
2N-COUNT 真空吸尘器 A vac is an electric machine which sucks up dust and dirt from carpets. Vac is an abbreviation for 'vacuum cleaner'. 真空吸尘器 [informal]