I. adverb Date: circa 1822 underhand , II. adjective Date: 1853 marked by secrecy, chicanery, and deception ; not honest and aboveboard ; sly , see: secret ~ly adverb ~ness noun
UNDERHANDED
Meaning of UNDERHANDED in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012