skylark

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of several larks of the genus Alauda of Eurasia and Africa, especially A. arvensis, having brownish plumage and noted for singing while in flight.
• intransitive verb To play actively and boisterously; frolic.

from The Century Dictionary.

• To engage in boisterous fun or frolic.
• noun The common lark of Europe, Alauda arvensis: so called because it mounts toward the sky and sings as it flies. Also called sky-laverock, rising-lark, field-lark, short-heeled lark, etc. The name extends to some other true larks, and also to a few of the pipits.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) A lark that mounts and sings as it files, especially the common species (Alauda arvensis) found in Europe and in some parts of Asia, and celebrated for its melodious song; -- called also sky laverock. See under lark.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A small brown passerine bird, Alauda arvensis, that sings as it flies high into the air.
• verb To jump about joyfully, frolic; to play around, play tricks.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb play boisterously
• noun brown-speckled European lark noted for singing while hovering at a great height