Definition of Alkyl group

Alkyl group: In chemistry, a group of atoms derived from an alkane (a hydrocarbon with no carbon-to-carbon multiple bonds) by the loss of a hydrogen atom.

Definition of Acapnia

Acapnia: Less than the normal level of
carbon dioxide in the blood. The opposite of hypercapnia. The origin
of the word "acapnia" is curious. It comes from the Greek "a-"
meaning "without" + "kapnos" meaning "smoke" so acapnia literally
means "smokeless" referring to carbon dioxide which is a principal
part of smoke.