freight rate vs freightage

freight rate and freightage both are nouns.

Word	Noun	Adjective	Verb	Adverb
freight rate	Yes	No	No	No
freightage	Yes	No	No	No

As nouns, freight rate and freightage are synonyms defined as:

freight rate and freightage: the charge for transporting something by common carrier

Other synonyms of freight rate include freight.

freight rate (noun)	freightage (noun)
the charge for transporting something by common carrier	transporting goods commercially at rates cheaper than express rates
	the charge for transporting something by common carrier