altar stone Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition noun. the flat stone forming the top of the altar in a Roman Catholic church Example Sentence The priest placed the item on the altar stone. Synonyms altar slab; mensa; upper slab of an altar Antonyms pillow Hear It! Say It! Write It! altar stone Switch to cursive Start Share with your friends: