Necessary - (Webster's 1828 Dictionary)
1. That must be; that cannot be otherwise; indispensably requisite. It is necessary that every effect should have a cause.
2. Indispensable; requisite; essential; that cannot be otherwise without preventing the purpose intended. Air is necessary to support animal life; food is necessary to nourish the body; holiness is a necessary qualification for happiness; health is necessary to the enjoyment of pleasure; subjection to law is necessary to the safety of persons and property.
3. Unavoidable; as a necessary inference or consequence from facts or arguments.
4. Acting from necessity or compulsion; opposed to free. Whether man is a necessary or a free agent is a question much discussed.
NECESSARY, n. A privy.