Merriam-Webster's Collegiate® Dictionary, 11th Edition
LEAF
I. noun (plural leaves; also leafs)
Usage: often attributive
Etymology: Middle English leef, from Old English lēaf; akin to Old High German loub leaf Date: before 12th century
1. a. a lateral outgrowth from a plant stem that is typically a flattened expanded variably shaped greenish organ, constitutes a unit of the foliage, and functions primarily in food manufacture by photosynthesis, a modified leaf (as a bract or sepal) primarily engaged in functions other than food manufacture, b. foliage , the leaves of a plant as an article of commerce, something suggestive of a leaf: as, a part of a book or folded sheet containing a page on each side, b. a part (as of window shutters, folding doors, or gates) that slides or is hinged, the movable parts of a table top, c. a thin sheet or plate of any substance ; lamina , metal (as gold or silver) in sheets usually thinner than foil, one of the plates of a leaf spring, leafless adjective leaflike adjective
II. verb
Date: 1611
intransitive verb to shoot out or produce leaves , to turn over pages especially to browse or skim , transitive verb to turn over the pages of