"a petty, feeble, or contemptible politician" [OED], 1640s, from Italian or Spanish politicastro, from politico, noun use of adjective meaning "political" (from Latin politicus; see political) + pejorative ending (see -aster).
1550s, "of or pertaining to a polity, civil affairs, or government;" from Latin politicus "of citizens or the state" (see politic (adj.)) + -al (1). Meaning "taking sides in party politics" (usually pejorative) is from 1749. Political prisoner first recorded 1860; political science is from 1779 (first attested in Hume). Political animal translates Greek politikon zōon (Aristotle, "Politics," I.ii.9) "an animal intended to live in a city; a social animal":
From these things therefore it is clear that the city-state is a natural growth, and that man is by nature a political animal, and a man that is by nature and not merely by fortune citiless is either low in the scale of humanity or above it ... inasmuch as he is solitary, like an isolated piece at draughts. [Rackham transl.]
word-forming element expressing incomplete resemblance (such as poetaster), usually diminutive and deprecatory, from Latin -aster, from a suffix forming nouns from verbs ending in Greek -azein; in later Latin generalized as a pejorative suffix, as in patraster "he who plays the father."
<a href="https://www.etymonline.com/word/politicaster">Etymology of politicaster by etymonline</a>
Harper, D. (n.d.). Etymology of politicaster. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/politicaster