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 (cf. Old Norse sa, Old Saxon saian, Middle Dutch sayen, Dutch zaaien, Old High German sawen, German säen, Gothic saian), from PIE root *se- (1) "to sow" (cf. Latin sero, past tense sevi, past participle satum "to sow;" Old Church Slavonic sejo, sejati; Lithuanian seju, seti "to sow"), source of semen, season (n.), seed (n.), etc. Figurative sense was in Old English.
Old English sugu, su "female of the swine," from Proto-Germanic *su- (cf. Old Saxon, Old High German su, German Sau, Dutch zeug, Old Norse syr), from PIE root *su- (cf. Sanskrit sukarah "wild boar, swine;" Avestan hu "wild boar;" Greek hys "swine;" Latin sus "swine," swinus "pertaining to swine;" Old Church Slavonic svinija "swine;" Lettish sivens "young pig;" Welsh hucc, Irish suig "swine; Old Irish socc "snout, plowshare"), possibly imitative of pig noise, a notion reinforced by the fact that Sanskrit sukharah means "maker of (the sound) 'su.' " Related to swine. As a term of abuse for a woman, attested from c.1500. Sow-bug "hog louse" is from 1750.