besieging vs siege

besieging and siege both are nouns.

Word	Noun	Adjective	Verb	Adverb
besieging	Yes	No	No	No
siege	Yes	No	No	No

As nouns, besieging and siege are synonyms defined as:

besieging and siege: the action of an armed force that surrounds a fortified place and isolates it while continuing to attack

Other synonyms of besieging include beleaguering, military blockade.

besieging (noun)	siege (noun)
the action of an armed force that surrounds a fortified place and isolates it while continuing to attack	the action of an armed force that surrounds a fortified place and isolates it while continuing to attack