-al

The suffix -al is the IUPAC nomenclature used in organic chemistry to form names of aldehydes containing the -(CO)H group. It was extracted from the word "aldehyde".

References

v t e Organic chemistry affixes
Carbon-based	-ane (alkane) -ene (alkene) -ine (unsaturated hydrocarbon) -yne (alkyne) alk- (saturated hydrocarbon) ar- (aromatic)
Oxygen-based	-al (aldehyde) -oate (ester) -oic acid (carboxylic acid) -ol (alcohol) -one (ketone) -ose (sugar)
Nitrogen-based	-ine (alkaloid) aza- (N replaces C)
Sulfur-based	thio- (S replaces O)
Counting axial atoms	meth- (1) eth- (2) prop- (3) but- (4) (and the rest are ordinary Greek/Latin numbers)
Other	-ase (enzyme) -yl (radical)