qualm

Concise Oxford English Dictionary © 2008 Oxford University Press:
qualm /kwɑːm, kwɔːm/

▶noun

• 1 a feeling of doubt or unease, especially about one's conduct.

• 2 archaic a momentary faint or sick feeling.

– derivatives
qualmish adjective.

– origin C16: perh. rel. to OE cw(e)alm ‘pain’, of Gmc origin.