COCK is the verb used to draw a light, heavy, or hand crossbow to prepare it for shooting. Cocking a crossbow forces the user into offensive stance and incurs 2 seconds of roundtime. If the character is encumbered then this may take additional roundtime. Dwarf, Burghal Gnome, and Forest Gnome characters have reduced penalty to encumbrance-based roundtime.
For crossbows, it is optional to manually COCK the bow prior to firing. If it is not pre-cocked then the FIRE command will COCK/FIRE in the same action with combined roundtime. Light crossbows and hand crossbows take 2 seconds to cock and 2 seconds to fire (4 seconds combined), while heavy crossbows take 2 seconds to cock and 3 seconds to fire (5 seconds combined).
For more information about operating crossbows, see Ranged Weapons.