› worksheets › third-gradeBrowse Printable 3rd Grade Synonyms and Antonym Worksheets ... One of the toughest parts of writing is trying to figure out the right words to use. When a word means the same thing as another word, it's called a synonym. Our 3rd grade synonyms and antonyms worksheets are a big help. Using these teacher-curated pages, your young learner will develop a wide vocabulary and gain access to fun activities.