Merriam-Webster's Collegiate® Dictionary, 11th Edition
SNEAK
I. verb (sneaked or snuck; sneaking)
Etymology: akin to Old English snīcan to sneak along, Old Norse snīkja
Date: 1594
intransitive verb to go stealthily or furtively ; slink , to act in or as if in a furtive manner, to carry the football on a quarterback sneak, transitive verb to put, bring, or take in a furtive or artful manner , see: lurk
Usage: From its earliest appearance in print in the late 19th century as a dialectal and probably uneducated form, the past and past participle snuck has risen to the status of standard and to approximate equality with sneaked. Indications are that it is continuing to grow in frequency. It is most common in the United States and Canada, but has also been spotted in British and Australian English.
II. noun
Date: circa 1643
a person who acts in a stealthy, furtive, or shifty manner,
2. a stealthy or furtive move, an unobserved departure or escape, sneaker 2, quarterback sneak ,
III. adjective
Date: circa 1859
carried on secretly ; clandestine , occurring without warning ; surprise