As nouns the difference between tan and tanto

is that tan is a yellowish-brown colour while tanto is a common type of Japanese dagger or knife. an alternative spelling of tantō|lang=en.

As an adjective tan

is of a yellowish-brown.

As a verb tan

is to change to a tan colour due to exposure to the sun.

As a numeral tan

is the second cardinal number two, formerly used in Celtic areas, especially Cumbria and parts of Yorkshire, for counting sheep, and stitches in knitting.See Wikipedia article on Yan Tan Tethera

As a proper noun Tan

is an English surname derived from the transliteration of various Asian surnames, particularly originating from China and Vietnam.

As an initialism TAN

is Total Acid Number, the measure of a lubricant's or crude oil's acidity.

As an adverb tanto is

so much; too much.