indefinite

Definitions:

Not limited; not precise or certain; not distinctly marked; vague or unsettled; in bot., applied to inflorescence in which the central or terminal flower is the last to expand; having more than twenty stamens; very numerous, as ovules or seeds.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (adjective) (adj.) (adjective)
Not exact; vague; uncertain; having no particular limit; too numerous or variable to be easily counted.
- The Winston Simplified Dictionary. By William Dodge Lewis, Edgar Arthur Singer. Published 1919. (adjective) (adj.) (adjective)
Not definite or limited; not precise.
- The Clarendon dictionary. By William Hand Browne, Samuel Stehman Haldeman. Published 1894. (adjective) (adj.) (adjective)
Not limited; not determinate; of no fixed number.
- A dictionary of scientific terms. By Henderson, I. F.; Henderson, W. D. Published 1920. (adjective) (adj.) (adjective)
INDEFINITENESS.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (noun) (n.) (noun)
Not limited: not precise or certain.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (adjective) (adj.) (adjective)
Indefinitely.
- The Winston Simplified Dictionary. By William Dodge Lewis, Edgar Arthur Singer. Published 1919. (adverb) (adv.) (adverb)
Not defined or determinate; not precise or certain; that has no determinate or certain limits.
- Nuttall's Standard dictionary of the English language. By Nuttall, P.Austin. Published 1914. (adjective) (adj.) (adjective)

Usage examples:

I had had an indefinite plan to secure his influence by saving him from the ruin which others threatened.
- By Wit of Woman by Arthur W. Marchmont
A man carrying what seemed to be a great deal of something indefinite was coming down the avenue towards her.
- The Pastor's Wife by Elizabeth von Arnim
Why- not exactly- my political plans are rather indefinite
- Jimmy Kirkland and the Plot for a Pennant by Hugh S. Fullerton