myria-

American  

1. a combining form meaning “10,000,” used especially in the names of metric units equal to 10,000 of the unit denoted by the base word.

   myriagram; myriameter.

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myria- British  

combining form

1. indicating a very great number

   myriapod

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Etymology

Origin of myria-

Combining form representing Greek mȳriás ten thousand; see myriad