Synonyms

underside

American

[uhn-der-sahyd] / ˈʌn dərˌsaɪd /

noun

an under or lower side.

underside British

/ ˈʌndəˌsaɪd /

noun

the bottom or lower surface

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of underside

First recorded in 1670–80; under- + side ¹

Vocabulary lists containing underside

Florida's B.E.S.T. Common Prefixes: under-

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Ajinomoto, the Japanese food company best known for commercializing monosodium glutamate, used its chemistry knowledge to make a specialized film used in the underside layer of a chip alongside T-glass.

From The Wall Street Journal • Feb. 8, 2026

On the underside of its cap are white gills and spores.

From Los Angeles Times • Jan. 16, 2026

The teen made up for his disappointment by putting the Indomitable Lions ahead on 55 minutes with a fierce shot from outside the box that flew into the net off the underside of the crossbar.

From Barron's • Dec. 31, 2025

The 26th seed from Scotland hit the underside of the table three times before holding his hand up in apology to the Alexandra Palace crowd as he left the stage.

From BBC • Dec. 15, 2025

The underside of Akira’s left arm was the worst.

From "Two Degrees" by Alan Gratz

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023