isr

(uncountable, espionage) Initialism of intelligence, surveillance, reconnaissance (“spycraft”). [(chiefly uncountable) The capacity of mind, especially to understand principles, truths, facts or meanings, acquire knowledge, and apply it to practice; the ability to comprehend and learn; the ability to process sentient experience to generate true beliefs with a justified degree of confidence.]

(countable, software) Initialism of interrupt service routine.

Initialism of Inuvialuit Settlement Region.

(US, obsolete) Initialism of interstate route.