English
ink sac
From ink + sac.
Ancient Greek ἔγκαυστον ‘burned-in’
Latin encaustum ‘purple ink used by Roman emperors to sign…’
Old French enque
Middle English ynke
English ink
Ancient Greek σᾰ́κκος ‘coarse cloth of hair, especially of goat's hair’
Latin saccus ‘a garment of sackcloth or haircloth’
Old French sac ‘bag’
French sac ‘bag, sack’
English sac
Today it means
noun A muscular bag found in certain cephalopods used to generate ink.
Language periods are conventional ranges, not dates for this word.
Etymograph / ink sac