Merriam-Webster's Collegiate® Dictionary, 11th Edition
SIP
I. verb (sipped; sipping)
Etymology: Middle English sippen; akin to Low German sippen to sip
Date: 14th century
intransitive verb to take a sip of something especially repeatedly, transitive verb to drink in small quantities, to take sips from, sipper noun
II. noun
Date: 15th century
a small draft taken with the lips, the act of sipping