1) Anything indispensable 2) Necessary 3) Needed 4) Needful 5) Required 1) Compulsory 2) Crucial 3) Desideratum 4) Essential 5) Necessary 6) Need 7) Needed 8) Needful 9) Obligation 10) Required 
• (a.) Required by the nature of things, or by circumstances; so needful that it can not be dispensed with; necessary; indispensable. • (n.) That which is required, or is necessary; something indispensable.
Req'ui·site noun That which is required, or is necessary; something indispensable. « God, on his part, has declared the requisites on ours; what we must do to obtain blessings, is the great business of us all to know.» Wake. 
The USS Requisite was an American Auk Class minesweeper of 890 tons displacement launched in 1942. The USS Requisite was powered by diesel engines providing a top speed of 18 knots and carried a complement of 105. She was armed with one 3 inch dual-purpose gun and two 40 mm anti-aircraft guns.
requisite Necessary or indispensable for something; or, something that is necessary or indispensable.
necessary for relief or supply