Oxalyl \Ox"a*lyl\, n. [Oxalic + -yl.]

(Chem.)
   (a) A hydrocarbon radical (C2O2) regarded as a residue of oxalic acid and occurring in derivatives of it.
   (b) An old name for carbonyl.
   (c) An old name for carboxyl.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Carboxyl \Car*box"yl\, n. [Carbon + oxygen + -yl.]

(Chem.) The complex radical, CO.OH, regarded as the essential and characteristic constituent which all oxygen acids of carbon (as formic, acetic, benzoic acids, etc.) have in common; -- called also oxatyl.

Source: Webster's Revised Unabridged Dictionary (1913)