A crenulate leaf.    From Wordnet, Princeton University. 

The lower pinnæ pinnately parted into three to five divisions, those of the fertile fronds oblong or linear-oblong; those of the sterile, obovate or ovate, crenulate, decurrent at the base.    From Wordnik.com.  [The Fern Lover's Companion A Guide for the Northeastern States and Canada] Reference

These are somewhat hyaline and are closely approximated, giving the impression of a tight-fitting crenulate casing about the lower half.    From Wordnik.com.  [Marine Protozoa from Woods Hole Bulletin of the United States Fish Commission 21:415-468, 1901] Reference

(Fig. 139.) Shell obtusely ovate; wide at the base of the spire; spire depressed; both lips crenulate, but most distinct upon the outer lip; resembles very closely a marginella.    From Wordnik.com.  [Report of the North-Carolina Geological Survey. Agriculture of the Eastern Counties: Together with Descriptions of the Fossils of the Marl Beds] Reference

Leaves simple, alternate, 2-4 inches long, smooth and bright green above, smooth and whitish beneath when fully grown; outline ovate-lanceolate to narrowly oblong-oval, crenulate-serrate to entire; apex acute, base acute and entire; leafstalk short; stipules toothed or entire.    From Wordnik.com.  [Handbook of the Trees of New England] Reference

Leaves 3-5 inches long, light green on the upper side, paler beneath, pubescent when young; outline ovate-obovate or orbicular, crenulate-serrate; teeth not bristle-tipped; apex abruptly acuminate; base wedge-shaped, rounded, somewhat heart-shaped, or narrowing to a short petiole more or less red-glandular near the blade; stipules usually linear, ciliate, soon falling.    From Wordnik.com.  [Handbook of the Trees of New England] Reference

Its leaves, radical, or carried on stolons, (vol. i., p. 158,) are sharp, or oval, crenulate, or heart-shape.    From Wordnik.com.  [Proserpina, Volume 2 Studies Of Wayside Flowers] Reference