A sleeve tattoo is a large tattoo, or a collection of smaller tattoos, usually themed in similar manner, that covers most or all of a person's arm, usually from shoulder to wrist.
The term sleeve is a reference to the tattoo's size similarity in coverage to a long shirt sleeve on an article of clothing. In this manner, the term is also used as a verb; for example, getting sleeved means to have one's entire arm tattooed. The term sleeve is also sometimes used in reference to a large leg tattoo that covers a person's leg in a similar manner.
Half-sleeves or quarter-sleeves are tattoos that cover only part of an arm, usually above the elbow, but can also be found below the elbow. The term sleeve implies complete tattoo coverage of a particular area, so a "half sleeve" is a tattoo that covers the entire upper or lower arm. A "quarter sleeve" usually covers the area of skin from the shoulder midway to the elbow.