Where does “pustulous” come from?

pustulous (English) comes from English pustule, from Middle English pustule, from Old French pustule, from Latin pustula, from Finnish pus-, from Proto-Indo-European bew- — "low-pitch humming noise".

pustulous (English): Bearing pustules; Resembling a pustule

Definitions

Bearing pustules; Resembling a pustule

Ancestry of “pustulous”, step by step

Step	Language	Word	Meaning
1	English	pustule	A small accumulation of pus in the epidermis or...
2	Middle English	pustule	—
3	Old French	pustule	pustule
4	Latin	pustula	inflamed sore, blister, pustule
5	Finnish	pus-	—
6	Proto-Indo-European	bew-	"low-pitch humming noise"

Every word from Proto-Indo-European bew- →Every word from Finnish pus- →Every word from Latin pustula →