Alanfi, I don't agree....
Chambers : a leave of absence, especially from military duty.
Collins: Noun. 1. leave of absence from military duty . 2 (American) a temporary laying-off of employees, usually because there is insufficient work to occupy them. Verb. 3. to grant a furlough to 4. US to lay off (staff) temporarily.
Oxford Dictionary Of English. Noun. Leave of absence, especially that granted to a member of the services or a missionary. Verb: grant leave of absence to.
The 'especially' in Chambers and the ODE indicates the leave isn't related solely to the military