jack of all trades

jack of all trades  {n.},  {informal} (Often followed by "master of none.")
A person who is knowledgeable in many areas. Can be used as praise, or as a derogatory remark depending on the context and the intonation.
Peter is a jack of all trades; he can survive anywhere!
"How come Joe did such a sloppy job?" Mary asked. "He's a jack of all trades," Sally answered.
Categories: derogatory informal noun