Antonym for "ad hoc"

You can use "universal, overall, versatile, general, multiuse, flexible".

Edit:

Ad-hoc / general-purpose: Able to accommodate multiple uses

You can use

universal : The definition of universal is relating to or affecting all.

ex 1: An example of universal used as an adjective is a universal curfew for a town which means that all members of that town must be home by a certain time.

ex 2: Adapted or adjustable to many sizes, uses, or devices: a universal remote control.

Versatile : The definition of versatile is having many uses.

Exclusively designed collections offer versatile, mix and match outfits, in a variety of color palettes.

overall : The definition of overall is including everything or in general.

ex 1: An example of overall used as an adjective is in the phrase "the overall taste of the pizza," which means the general taste of the pizza.

systematic:

adjective

Done or acting according to a fixed plan or system; methodical:

ad hoc:

adjective& adverb

Created or done for a particular purpose as necessary: