Webster's Revised Unabridged Dictionary · 1913

Oxalyl

Oxalyl , noun

[Oxalic + -yl.]

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