pith helmet vs topi

pith helmet and topi both are nouns.

Word	Noun	Adjective	Verb	Adverb
pith helmet	Yes	No	No	No
topi	Yes	No	No	No

As nouns, pith helmet and topi are synonyms defined as:

pith helmet and topi: a lightweight hat worn in tropical countries for protection from the sun

Other synonyms of pith helmet include pith hat, sun helmet, topee.

pith helmet (noun)	topi (noun)
a lightweight hat worn in tropical countries for protection from the sun	a large South African antelope; considered the swiftest hoofed mammal
	a lightweight hat worn in tropical countries for protection from the sun