Merriam-Webster's Collegiate® Dictionary, 11th Edition
SHRINK
I. verb (shrank or shrunk; shrunk or shrunken; shrinking)
Etymology: Middle English, from Old English scrincan; akin to Middle Dutch schrinken to draw back Date: before 12th century intransitive verb to contract or curl up the body or part of it ; huddle , cower ,
2. to contract to less extent or compass, to become smaller or more compacted, to lose substance or weight, to lessen in value ; dwindle ,
3. to recoil instinctively (as from something painful or horrible) , to hold oneself back ; refrain , transitive verb to cause to contract or shrink, see: contract shrinkable adjective shrinker noun
II. noun
Date: 1590
the act of shrinking, shrinkage , a clinical psychiatrist or psychologist