Merriam-Webster Collegiate Dictionary - plenty

 I. noun  Etymology: Middle English plente, from Anglo-French plente, from Late Latin plenitat-, plenitas, from Latin, fullness, from plenus full — more at full  Date: 13th century  1.  a. a full or more than adequate amount or supply had ~ of time to finish the job  b. a large number or amount in ~ of trouble  2. the quality or state of being copious ; plentifulness  II. adjective  Date: 14th century  1. plentiful in amount, number, or supply if reasons were as ~ as blackberries — Shakespeare  2. ample ~ work to be done — Time Usage:  Many commentators object to use of sense 2 in writing; it appears to be limited chiefly to spoken English. Sense 1 is literary but is no longer in common use.  III. adverb  Date: 1842 more than sufficiently ; to a considerable degree the nights were ~ cold — F. B. Gipson Usage:  Many handbooks advise avoiding the adverb ~ in writing; “use very, quite, or a more precise word,” they advise. Actually ~ is often a more precise word than its recommended replacements; very, fully, or quite will not work as well in these typical quotations it's already ~ hot for us in the kitchen without some dolt opening the oven — C. H. Bridges may not be rising quite as rapidly as other health costs, but it is going up ~ fast — Changing Times. It is not used in more formal writing.