From the Japanese 'word' shotacon (an abbreviated form of 'shotaro complex'... Shotaro being a very common male name).

A shota is a male character who resembles and appears to be young. This phrase is used to refer to humans, humanoids, and anthros alike.

Please keep in mind not every shota will actually be underaged, as the phrase itself is mostly used to describe a "youthful appearance".

* Note: This should only be tagged for explicit and sexually suggestive content.

See also:

• young
• loli (term for female characters who resemble/appear to be preadolescent)
• shota