1848, "a period when business is down," from off- (adj.) (see off (prep.)) + season (n.).

"suitable as to the time or season of the year," c. 1300, sesounable, originally of weather, "favorable," from Old French saisonable, Anglo-French seisonnable, from seison, saison (see season (n.)). From early 15c. as "occurring at the right season, opportune." Related: Seasonably; seasonableness.

"pertaining to the seasons; relating to a season," 1829, from season (n.) + -al (1). Of workers or employment, from 1904. Related: Seasonally; seasonality.

mid-15c., "flavored, spiced," past-participle adjective from season (v.). Meaning "fit for use, matured, hardened" (of timber, etc.), is from 1540s; that of "acclimatized, accustomed" (of persons, animals, etc.) is from 1640s.

1510s, "act or time of impregnation" (a sense now obsolete); c. 1600, "act of adding flavor;" 1570s, "something added to food to impart flavor," also figurative; verbal noun from season (v.). Of enslaved persons, "become inured to the conditions of slavery," by 1771.

Middle English souen, from Old English sawan "to scatter seed upon the ground or plant it in the earth, disseminate" (class VII strong verb; past tense seow, past participle sawen), from Proto-Germanic *sean (source also of Old Norse sa, Old Saxon saian, Middle Dutch sayen, Dutch zaaien, Old High German sawen, German säen, Gothic saian).

This is reconstructed to be from PIE root *sē- "to sow," source of semen, season (n.), seed (n.). The figurative sense of "spread abroad, disseminate" was in Old English; of physical things other than seed, "scatter over, besprinkle," mid-14c. Related: Sowed, sown; sowing. Sowing machine "device for sowing seed" is by 1812.

1580s, "not made palatable by seasoning," from un- (1) "not" + past participle of season (v.). Meaning "not habituated by experience" is recorded from c. 1600.

Proto-Indo-European root meaning "to sow." 

It forms all or part of: disseminate; inseminate; seed; seme (adj.); semen; seminal; seminar; seminary; semination; sinsemilla; sow (v.); season.

It is the hypothetical source of/evidence for its existence is provided by: Latin serere "to sow;" Old Church Slavonic sejo, sejati; Lithuanian sju, sti "to sow;" Old English sawan "to sow;" Old Prussian semen "seed," Lithuanian smenys "seed of flax," Old Church Slavonic seme, Old High German samo, German Same; Old English sed, sd "that which may be sown; an individual grain of seed."