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-

Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!

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.

To investigate the process, the team combined a highly detailed map of the underside of the Fimbulisen Ice Shelf with a high resolution computer model of the ocean cavity beneath it.

From Science Daily • May 10, 2026

Serbian midfielder Samardzic held his composure to slam home the penalty left-footed with the ball glancing the underside of the crossbar on its way into the net.

From Barron's • Feb. 25, 2026

A fluffy, faux-wool sherpa underside sits next to the skin.

From The Wall Street Journal • Jan. 23, 2026

France legend Zinedine Zidane has a claim for taking the most high-pressure Panenka, in the 2006 World Cup final with his penalty hitting the underside of the crossbar and just crossing the line.

From BBC • Jan. 19, 2026

The roots of the ceiling begin to worm, lengthening like vines and crawling across the underside of the hill.

From "The Cruel Prince" by Holly Black

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