a. Full of use, advantage, or profit; producing, or having power to produce, good; serviceable for any end or object; helpful toward advancing any purpose; beneficial; profitable; advantageous;
To what can I useful! Milton. [ 1913 Webster ]
adv. In a useful manner. [ 1913 Webster ]
n. The quality or state of being useful; utility; serviceableness; advantage. Addison. [ 1913 Webster ]