
Spanish word acostar comes from Proto-Indo-European *kost-, and later Latin costa ((anatomy) a rib. A side, a wall.)
*kost- (Proto-Indo-European)
costa (Latin)
(anatomy) a rib. A side, a wall.
costa (Spanish)
Coast, shore. Expense, costs in certain expressions.
acostar (Spanish)
(nautical) to land, put in, berth. (transitive) to lay. (transitive) to put to bed.