/ Thesaurus / O Synonyms of o level Find synonyms for: Noun1. General Certificate of Secondary Education, GCSE, O level, grade, level, tierusage: the basic level of a subject taken in schoolWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: diligent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language