Regarding, re.

Initialism of Royal Engineers, a regiment in the British Army.

(computing theory) Abbreviation of "recursively enumerable"; the class of decision problems for which a 'yes' answer can be verified by a Turing machine in a finite amount of time.

(chiefly law) In the matter of; with regard to.

(law) Abbreviation of resource. / (law) Abbreviation of resources.

(informal) contracted form of are (inflection of the verb "to be")

Initialism of red ear syndrome.

The act of opening something for the third time.

simple past tense and past participle of re-lay

(transitive) To lay (for example, flooring or railroad track) again.