cuboid Get Printable Handwriting (cu-boid) 2 syllables Learn It! Spelling Test Definition adjective. 1 like a cube in shape; 2.designating a cubelike bone on the outer side of the foot.noun. 1 the cuboid bone; 2.a geometric shape with six rectangular sides. Example Sentence The cuboid has 6 faces. Synonyms cubelike; cube-shaped; cubical; cubiform Antonyms circle Share with your friends: