bachelor of science Usage: usually capitalized B&S 1.: the recipient of a bachelor's degree which usually signifies that the recipient has done the greater part of his course work in the sciences with some specialization in a particular science 2.: the degree making one a Bachelor of Science — abbr. B.S., B.Sc., S.B. < the degree of Bachelor of Science in agronomy > < a B.S. in chemical engineering > < a B.Sc. in architecture >