a, b, e, p, t, y are letters that make 'type AB'
type, type A, AB, ab, pe, Ab are words within 'type AB'
1 possible definitions for 'type AB'
Under this definition, type ab is a noun and has the following properties:
AB, group AB have the same meaning as 'type AB'
'type AB' can be a type of blood group, blood type.