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 (mə-măt′əs, -mä′təs, -mā′-, măm′ə-təs)
A cloud formation consisting of rounded, usually smooth protuberances that appear to hang down from the base of cumulonimbus or other clouds.

[From Latin mammātus, having breasts, from mamma, breast; see mā- in Indo-European roots.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Physical Geography) a bumpy, breast-shaped cloud
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
References in periodicals archive ?
IOP Date and location Observed phenomena 1 9 May 2015 Sea-breeze front Titusville, Florida 2 10 May 2015 Sea-breeze front; distant ordinary Rockledge, Florida thunderstorms 3 11 May 2015 Sea-breeze front and convergence; Grand Island, Florida ordinary thunderstorms 4 12 May 2015 Sea-breeze front and convergence; Hastings, Florida strong thunderstorms; weak rotation 5 15 May 2015 Strong ordinary thunderstorms; Pasco County, Florida Gulf Coast sea-breeze front 6 16 May 2015 Gulf Coast sea-breeze front; Clearwater, Florida distant thunderstorms 7 19 May 2015 Sea-breeze front; numerous ordinary Hastings, Florida thunderstorms 8 20 May 2015 Sea-breeze front Rockledge, Florida 9 20 May 2015 Severe thunderstorms; shelf Daytona Beach, Florida clouds, mammatus, and gust fronts Table 3.
Mumbai, India, September 18, 2016 --( Stellar Analytics, a Market Research and Outsourcing professional services firm, today announced a partnership with Mammatus Ltd.
This week we saw the unusual cloud formations, mammatus clouds, over Newcastle which surprised many of you.
Journal photographer Simon Greener captured a photo of the "mammatus" clouds above Byker.
I learned to watch for the perilous violet-jade clouds with v-shaped mammatus; how to lie in a ditch if I saw a funnel cloud; how to barricade myself in the interior bathroom in the event of a full-on lightning storm, hurricane, or tornado.
Mammatus clouds -These are some of the most unusual and distinctive clouds formations with a series of bulges or pouches emerging through the base of the cloud.They are usually formed in association with large cumulonimbus clouds, particular when these are forming large thunderstorms.
Mammatus clouds over Byker, Newcastle | SIMON GREENER
The event also featured Canadian-born artist Kelly Richardson, whose work involves melding real footage with digital elements, such as combining a billowing factory with beautiful Mammatus clouds.