al·​to·​stra·​tus ˌal-tō-ˈstrā-təs How to pronounce altostratus (audio) -ˈstra- How to pronounce altostratus (audio)
plural altostrati ˌal-tō-ˈstrā-ˌtī How to pronounce altostratus (audio)
: a fairly uniform mid-altitude layer of gray cloud darker than cirrostratus see cloud illustration

Example Sentences

Recent Examples on the Web Mid-level clouds are usually gray and are identified as either altocumulus, altostratus, or nimbostratus. Catherine Zuckerman, National Geographic, 24 Apr. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'altostratus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History


New Latin, from Latin altus + New Latin -o- + stratus

First Known Use

1890, in the meaning defined above

Time Traveler
The first known use of altostratus was in 1890

Dictionary Entries Near altostratus

Cite this Entry

“Altostratus.” Dictionary, Merriam-Webster, Accessed 21 Mar. 2023.

Kids Definition


al·​to·​stra·​tus ˌal-tō-ˈstrāt-əs How to pronounce altostratus (audio) -ˈstrat- How to pronounce altostratus (audio)
: a layer of gray cloud similar to cirrostratus but darker and at a lower level

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