under-

1. a prefixal use of under, as to indicate place or situation below or beneath (underbrush; undertow); lower in grade or dignity (undersheriff; understudy); of lesser degree, extent, or amount (undersized); or insufficiency (underfeed).

prefix

1. below or beneathunderarm; underground
2. of lesser importance or lower rankundersecretary
3. to a lesser degree than is proper; insufficient or insufficientlyundercharge; underemployed
4. indicating secrecy or deceptionunderhand