Definition of under- in US English:

under-

prefix

  • 1Below; beneath.

    ‘underclothes’
    ‘undercover’
    1. 1.1 Lower in status; subordinate.
      ‘undersecretary’
  • 2Insufficiently; incompletely.

    ‘undernourished’

Pronunciation

under-

/ˈəndər//ˈəndər/