-aster1

1.
a diminutive or pejorative suffix denoting something that imperfectly resembles or mimics the true thing:
criticaster; poetaster, oleaster.
Origin
< Latin

-aster2

1.
Chiefly Biology. a combining form with the meaning “star,” used in the formation of compound words:
diaster.
Origin
< Greek astḗr star; cf. astro-
British Dictionary definitions for -aster

-aster

suffix
1.
a person or thing that is inferior or bears only a poor resemblance to what is specified: poetaster
Word Origin
from Latin: suffix indicating imperfect resemblance
Word Origin and History for -aster

word-forming element expressing incomplete resemblance (e.g. poetaster), usually diminutive and deprecatory, from Latin, from Greek -aster, suffix originally forming nouns from verbs ending in -azein, later generalized as a pejorative suffix, e.g. Greek patraster "he who plays the father."