-ster Suffix

1. Someone who is, or who is associated with, or who does something specified.
2. (humorous, sometimes offensive) A diminutive appended to a person's name.

Relatively uncommon for agent nouns, compared to more usual -er and -or; primarily used for single-syllable words. Also informal, particularly in contemporary productive use – compare hipster, scenester, bankster; older terms such as barrister do not have this casual connotation, however.

Sometimes used in proper names, e.g. Napster (file-sharing software), Blockster (Brandon Block, disc jockey)

In older words, used as a suffix for jobs that were held by women, e.g., webster (a female webber, or weaver), baxter (a female baker), spinster (a female spinner), brewster (a female brewer).