heterodactyl

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

• adjective Having a zygodactyl foot in which the third and fourth toes project forward and the first and second toes project backward, as in the trogons.

from The Century Dictionary.

• Having the digits irregular or peculiar in size, form, or position. Also heterodactylous.

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

• adjective (Zoöl.) Heterodactylous.

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

• adjective zoology heterodactylous

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

• adjective (of bird feet) having the first and second toes directed backward the third and fourth forward