Maintain, v. t. [imp. & p. p. Maintained; p. pr. & vb. n. Maintaining.]
Etymology: [OE. maintenen, F. maintenir, properly, to hold by the hand; main hand (L. manus) + F. tenir to hold (L.tenere). See Manual, and Tenable.]
1. To hold or keep in any particular state or condition; to support; to sustain; to uphold; to keep up; not to suffer to fail or decline; as, to maintain a certain degree of heat in a furnace; to maintain a fence or a railroad; to maintain the digestive process or powers of the stomach; to maintain the fertility of soil; to maintain present reputation.
2. To keep possession of; to hold and defend; not to surrender or relinquish. God values . . . every one as he maintains his post. Grew.
3. To continue; not to suffer to cease or fail. Maintain talk with the duke. Shak.
4. To bear the expense of; to support; to keep up; to supply with what is needed. Glad, by his labor, to maintain his life. Stirling. What maintains one vice would bring up two children. Franklin.
2 more senses
5. To affirm; to support or defend by argument. It is hard to maintain the truth, but much harder to be maintained by it. South.
Syn. -- To assert; vindicate; allege. See Assert.
Shades of meaning
Fernald has no entry of its own for maintain; he lists it under allege, keep, state, support.
Where he writes about it:
We keep, observe, or celebrate a festival; we keep or hold a prisoner in custody; we keep or preserve silence, keep the peace, preserve order--preserve being the more formal word; we keep or maintain a horse, a servant, etc.; a man supports his family; we keep or obey a commandment; keep or fulfil a promise. — from keep
In the expressions to keep a secret, keep one's own counsel, keep faith, or keep the faith, such words as preserve or maintain could not be substituted without loss. — from keep
To maintain is to keep in a state or condition, especially in an excellent and desirable condition; as, to maintain health or reputation; to maintain one's position; to maintain a cause or proposition is to hold it against opposition or difficulty. — from support
To support may be partial, to maintain is complete; maintain is a word of more dignity than support; a man supports his family; a state maintains an army or navy. — from support