PREFIX
ac- to, toward, near
il- in, into

ROOT
cumul mass, heap
lumin light

SUFFIX
-ary someone or something that belongs to
-ate to make, to act
-ive performing or tending towards
-ous having the quality of

WORDS AND DEFINITIONS
accumulate - to gather or pile up little by little
cumulative - gradually building up
illuminate - to give light to
luminary - an object, like a star, that gives off light; a famous person ("star")
luminous - giving off or reflecting light