Merriam-Webster's Collegiate® Dictionary, 11th Edition
PRIM
I. transitive verb (primmed; primming)
Etymology: origin unknown
Date: 1706
to give a prim or demure expression to , to dress primly,
II. adjective (primmer; primmest)
Date: 1709
1. stiffly formal and proper ; decorous , prudish , neat , trim , primly adverb primness noun
III. abbreviation primary, primitive