Dictionary:

dabbler

  (dăb'lər)

One who engages in an activity superficially or without serious intent. See synonyms at amateur.

noun

One lacking professional skill and ease in a particular pursuit: amateur, dilettante, nonprofessional, smatterer, uninitiate. See ability/inability.

Definition: amateur
Antonyms: professional

The noun has 2 meanings:

Meaning #1: an amateur who engages in an activity without serious intentions and who pretends to have knowledge
  Synonyms: dilettante, sciolist

Meaning #2: any of numerous shallow-water ducks that feed by upending and dabbling
  Synonym: dabbling duck