Where does “iffy” come from?

iffy (English) comes from English -y, from Middle English -y, from Old English -iġ, from Proto-West Germanic -g, from Proto-Germanic -gaz, from Proto-Indo-European -ḱos — -y, -ic.

iffy (English): Of dubious authenticity, legitimacy or legality;...

Definitions

Of dubious authenticity, legitimacy or legality;...

Ancestry of “iffy”, step by step

Step	Language	Word	Meaning
1	English	-y	Added to nouns and adjectives to form adjectives...
2	Middle English	-y	Designates an adjective, in many cases formed by...
3	Old English	-iġ	-y, -ic
4	Proto-West Germanic	-g	Forms adjectives from nouns and verbs with a...
5	Proto-Germanic	-gaz	-y
6	Proto-Indo-European	-ḱos	-y, -ic

Words derived from “iffy”

iffiness
iffily

Every word from Proto-Indo-European -ḱos →Every word from English -y →Every word from Old English -iġ →