Dabbling is a term used to explain when a practitioner practices with multiple forms of magic rather than remain grounded to one. These practitioners are called Dabblers.
Dabbling combines everything from Shamanism to Diabolism and everything in-between, with the primary point being that they neither excel nor flourish in any field they dabble in, but can use it as a novice would or better.
Dabbling is frowned upon, at least in Jacobs' Bell, due to the fact that it is dangerous and leads to more mistakes if you aren't careful, and the practitioner isn't showing commitment and trying to master a specific field, even if they have more proficiency in one than another.
Someone who uses multiple arts to greater effect, rather than mere bits and pieces, is a Sorcerer.