saturnine (adj.)

Old English Sætern, name of the Roman god, also, in astronomy, the name of the most remote planet (then known); from Latin Saturnus, originally a name of an Italic god of agriculture, possibly from Etruscan. Derivation from Latin serere (past participle satus) "to sow" is said to be folk-etymology.

An ancient Italic deity, popularly believed to have appeared in Italy in the reign of Janus, and to have instructed the people in agriculture, gardening, etc., thus elevating them from barbarism to social order and civilization. His reign was sung by the poets as "the golden age." [Century Dictionary]

Identified with Greek Kronos, father of Zeus. Also the alchemical name for lead (late 14c.). In Akkadian, the planet was kaiamanu, literally "constant, enduring," hence Hebrew kiyyun, Arabic and Persian kaiwan "Saturn."

also -in, adjectival word-forming element, Middle English, from Old French -in/-ine, or directly from Latin suffix -inus/-ina/-inum "of, like," forming adjectives and derived nouns, as in divinus, feminus, caninus; from PIE adjectival suffix *-no- (see -en (2)).

The Latin suffix is cognate with Greek -inos/-ine/-inon, and in some modern scientific words the element is from Greek. Added to names, it meant "of or pertaining to, of the nature of" (Florentinus), and so it also was commonly used in forming Roman proper names, originally appellatives (Augustinus, Constantinus, Justinus, etc.) and its descendants in Romanic languages continued active in name-forming. The Latin fem. form, -ina, was used in forming abstracts (doctrina, medicina). Relics of the attempt to continue a distinction between Latin -ina and -inus account for the English hesitation in spelling between -in and -ine.