Um Definition

um, uō
interjection
Used to express doubt or uncertainty or to fill a pause when hesitating in speaking.
American Heritage
Webster's New World

(chiefly US) Expression of confusion or space filler in conversation. See uh.

Um, I don't know.
Let's see... um... how about this?
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preposition

Alternative form of umbe.

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verb
(intransitive) To make the um sound to express confusion or hesitancy.
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noun
Alternative spelling of µm.
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pronoun

(slang) An unstressed form of them.

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suffix
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(chemistry) Forms the ends of the names of certain elements (such as molybdenum and platinum).

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Denotes transitive verbs in the trade pidgins used between English-speakers and indigenous populations; used derogatorily by extension in English by addition to any verb, transitive or not.
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abbreviation

The ccTLD for United States Minor Outlying Islands as assigned by the IANA.

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prefix

(no longer productive, obsolete except dialectally, chiefly Scotland) Prefix meaning around, about.

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Other Word Forms of Um

Noun

Singular:
um
Plural:
a 1

Origin of Um

  • From Middle English um-, umbe-, embe-, from Old English ymb-, ymbe- (“around”), from Proto-Germanic *umbi (“around, about, by, near”), from Proto-Indo-European *ambʰi (“by, around”). Cognate with Dutch om- (“around”), German um- (“around”), Latin amb- (“around, about”), Latin ambi- (“both”), Ancient Greek ἀμφί (amphí-, “around, about”), Sanskrit अभि (abhi, “against, about”). More at umbe.

    From Wiktionary

  • From Middle English um, from Old Norse um, umb (“around, about"), from Proto-Germanic *umbi (“around"), from Proto-Indo-European *ambÊ°i- (“by, around"). Cognate with Old English ymbe (“around"). More at umbe.

    From Wiktionary

  • From the homographic case endings of the nominative, accusative, and vocative forms of numerous neuter Latin second declension nouns.

    From Wiktionary

  • A Latin-script rendering of µm.

    From Wiktionary

  • Contracted from them

    From Wiktionary