/ Thesaurus / S Synonyms of sei whale Find synonyms for: Noun1. sei whale, Balaenoptera borealis, rorqual, razorbackusage: similar to but smaller than the finback whaleWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: loathe Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language