A ravine or gully, especially in southern Asia.
[Bengali and Hindi nālā, channel, nullah, and similar forms in other Indic languages, all from Middle Indic nāḷa, nāla, hollow stalk, tube, from Sanskrit nāḍaḥ, from naḍaḥ, reed, variant (perhaps influenced by Dravidian words akin to Kannada naḷ, reed) of nadaḥ; akin to Persian nay, reed, flute, Armenian net, arrow, and Hittite nātaš, reed, arrow, and perhaps further akin to Sanskrit nadati, he roars, howls, cries.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.