It is commonly believed that the original root word of "tattoo" comes from the Tongan or the Tahitian word tatau, meaning to mark or strike twice (the latter referring to traditional methods of applying the designs).[1] The first syllable "ta", meaning "hand", is repeated twice as an onomatopoeic reference to the repetitive nature of the action, and the final syllable "U" translates to "color".[citation needed] The instrument used to pierce the skin in Polynesian tattooing is called a hahau, the syllable "ha" meaning to "strike or pierce".

The OED gives the etymology of tattoo as "In 18th c. tattaow, tattow. From Polynesian (Tahitian, Samoan, Tongan, etc.) tatau. In Marquesan, tatu." The first closest known usage of the word in English was recorded in the diary of Captain James Cook in 1769 during his voyage to the Marquesas Islands. The text reads, “...they print signs on people’s body and call this tattaw”, referring to the Polynesian customs.[citation needed] Sailors on the voyage later introduced both the word and reintroduced the concept of tattooing to Europe.

In Japanese the most common word used for traditional designs or those that are applied using traditional methods is irezumi ("insertion of ink"), while "tattoo" is used for non-Japanese designs.

Tattoo enthusiasts may refer to tattoos as "tats," "ink," "art," or "work," and to tattooists as "artists." The latter usage is gaining greater support, with mainstream art galleries holding exhibitions of tattoo designs and photographs of tattoos. Tattoo designs that are mass-produced and sold to tattoo artists and studios and displayed in shop are known as flash.