lark

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various chiefly Old World birds of the family Alaudidae, especially the skylark, having a sustained, melodious song.
2. n. Any of several similar birds, such as the meadowlark.
3. n. A carefree or spirited adventure.
4. n. A harmless prank.
5. v. To engage in spirited fun or merry pranks.

Century Dictionary and Cyclopedia

1. n. A small oscine passerine bird of the family Alaudidæ. Larks are mostly insectivorous migratory birds of Europe, Asia, and Africa, the only true larks found in the western hemisphere being those of the genus Eremophila, excepting the occasional occurrence of the skylark as a straggler. Africa is the richest in species. They are chiefly birds of the open country; they nest on the ground, and some are famous for soaring and singing. About 100 species are described, leading genera of which are Eremophila, Alauda, Melanocorypha, Certhilauda, Mirafra, Megalophonus, and Pyrrhulauda. The few species which are well known are generally distinguished by qualifying prefixes: as, the skylark, Alauda arvensis; the wood-lark, Alauda arborea; the shore-lark, Eremophila alpestris. See the compounds, and cuts under Alauda, Eremophila, and skylark.
2. n. A bird like or likened to a lark, but not one of the Alaudidæ: with a distinguishing prefix: as, the titlark, meadow-lark, bunting-lark, bushlark, horse-lark, etc. Such birds are chiefly the titlarks or pipits (see Anthus), and various kinds of finches and buntings.
3. n. A kind of sandpiper.
4. To catch or hunt larks.
5. n. A merry or hilarious adventure; a jovial prank or frolic; sport: as, to go on a lark.
6. To frolic; make sport; do anything in a sportive haphazard way.

Wiktionary

1. n. A romp, frolic, some fun.
2. n. A prank.
3. v. To sport, engage in harmless pranking.
4. v. To frolic, engage in carefree adventure.
5. n. Any of various small, singing passerine birds of the family Alaudidae.
6. n. Any of various similar-appearing birds, but usually ground-living, such as the meadowlark and titlark.
7. n. One who wakes early; one who is up with the larks.
8. v. To catch larks.

GNU Webster's 1913

1. n. colloq. A frolic; a jolly time.
2. v. colloq. To sport; to frolic.
3. n. (Zoöl.) Any one numerous species of singing birds of the genus Alauda and allied genera (family Alaudidæ). They mostly belong to Europe, Asia, and Northern Africa. In America they are represented by the shore larks, or horned larks, of the genus Otocoris. The true larks have holaspidean tarsi, very long hind claws, and, usually, dull, sandy brown colors.
4. v. To catch larks.

WordNet 3.0

1. n. any of numerous predominantly Old World birds noted for their singing
2. v. play boisterously
3. n. any carefree episode
4. n. North American songbirds having a yellow breast
5. n. a songbird that lives mainly on the ground in open country; has streaky brown plumage