tardus

Etymology
, according to De Vaan. Possibly.

Adjective

 * 1) slow, sluggish
 * 2) tardy
 * 3) late, lingering
 * 4) dull, stupid, slow-witted
 * 1) late, lingering
 * 2) dull, stupid, slow-witted
 * 1) dull, stupid, slow-witted
 * 1) dull, stupid, slow-witted