sizer I. sizer variant of sizar II. siz·er\ˈsīzə(r)\noun (-s) Etymology:size (II) + -er 1.: one that determines or sorts by sizes or checks for size < an orange sizer > 2.: one that shapes or surfaces articles to the required size < timber sizer > 3.: clocker III. sizernoun (-s) Etymology:size (IV) + -er 1.: one that applies size 2.: one that sizes felt hat bodies