Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
underhand is an adjective and adverb meaning "with hand brought forward and up from below shoulder level". It carries 4 recorded senses.
with hand brought forward and up from below shoulder level
“an underhand pitch”
“an underhand stroke”
sport
marked by deception
“achieved success in business only by underhand methods”
slyly and secretly
“Mean revenge, committed underhand”
“oldline aristocratic diplomats underhandedly undermined the attempt...to align Germany with the Western democracies”
Definitions, synonyms and semantic relations for underhand come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.