-al

turns a noun or root into an adjective meaning related to or characterized by it

Spelled -al, -ial · -alis 'related to, belonging to'

Latin -alis meant belonging to: annual returns belong to a year, regional customs to a region, and cordial warmth to the heart.

Words built from it

natural — existing in nature rather than made artificially
natur- (birth or nature) + -al (related to)
annual — happening once every year
annu- (year) + -al (related to)
regional — connected with a particular area
region + -al (related to)
cordial — warm and friendly
cord- (heart) + -ial (characterized by)
filial — relating to a child's duties or feelings toward a parent
fili- (son or child) + -al (related to)
proverbial — connected with a proverb or widely known
proverb + -ial (related to)

valuable — formed from value + -able; its 'al' belongs to value, not the -al suffix

-able/-ible — turns a verb into an adjective meaning capable of, fit to be, or worthy of the action
-cide — forms words naming an act of killing or the person or substance that kills
-en — turns an adjective or noun into a verb meaning to make or become that quality
-ful — turns a noun into an adjective meaning full of or strongly marked by it
-ic — turns a noun into an adjective meaning related to or characterized by it