shell out verb 2noun 1forms 3 verb2 •(informal) To pay money, to disburse; especially, to pay a great deal of money.Do you think we should shell out for the extra options package? •To use a program's "shell escape" function to execute an unrelated command or to invoke a subsidiary, interactive shell. noun1 •(no longer used) A game played on a billiard table, a variation of pool.I have more than once had to lend a commercial money to pay his fare home; as he had played shell-out and lost the lot. — 1875 formsshelled out · shelling out · shells out