Save This Word!

a combining form meaning “having a mouth” of the kind or number specified by the initial element: monostomous.
Should you take this quiz on “shall” versus “should”? It should prove to be a quick challenge!
Question 1 of 6
Which form is used to state an obligation or duty someone has?

Origin of -stomous

<Greek -stomos -mouthed, adj. derivative of stóma mouth; see -stome, -ous

Words nearby -stomous

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022


What does -stomous mean?

The combining formstomous is used like a suffix meaning “having a mouth or opening.” The first element of words containing -stomous specify the kind or number of mouths or openings the organism has. It is used in a few, rare, obsolete scientific terms, especially in biology and zoology.

The form -stomous comes from the Greek stóma, meaning “mouth.” This root is the source of the English word stoma (a technical term for a mouth, among other senses) and is related to stomach. Stomach? Our stomachs and mouths are certainly connected—and etymologically so, too. Discover the connection at our entry for the word.

Closely related to -stomous are -stome and -stomy. Corresponding forms of -stomous combined to the beginning of words are stomato- and stomat-. Learn more about the specific applications of these forms at our Words That Use articles for them.

Examples of -stomous

An example of a term from biology that features the combining form -stomous is monostomous, meaning “having a single mouth or opening.”

The form mono- means “single” or “one.” The rest of the word, -stomous, means “having a mouth.” Monostomous literally translates to “one-mouthed.”

What are some words that use the combining form -stomous?

  • cytostomous
  • hypostomous
  • gnathostomous
  • plagiostomous

What are some other forms that -stomous may be commonly confused with?

Keep in mind that -ous is a suffix used to form a great many words in English, from stupendous to stannous. While it is related to the -ous in -stomous, -ous in these words—as well as a multitude of others, from nervous to glorious—is not indicating “cut” or “divided.” Learn more at our entry for -ous.

Break it down!

Cytostomous is a rare adjective form of cytostome, “the mouth of a protozoan.” Given that cyto- means “cell,” what does cytostomous literally translate to?

British Dictionary definitions for -stomous


adj combining form
having a specified type of mouthmonostomous
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