escapee (n.)

c. 1300, transitive and intransitive, "free oneself from confinement; extricate oneself from trouble; get away safely by flight (from battle, an enemy, etc.)," from Old North French escaper, Old French eschaper (12c., Modern French échapper), from Vulgar Latin *excappare, literally "get out of one's cape, leave a pursuer with just one's cape," from Latin ex- "out of" (see ex-) + Late Latin cappa "mantle" (see cap (n.)). Mid-14c., of things, "get or keep out of a person's grasp, elude (notice, perception, attention, etc.);" late 14c. as "avoid experiencing or suffering (something), avoid physical contact with; avoid (a consequence)." Formerly sometimes partly Englished as outscape (c. 1500). Related: Escaped; escaping.

word-forming element in legal English (and in imitation of it), representing the Anglo-French -é ending of past participles used as nouns (compare -y (3)). As these sometimes were coupled with agent nouns in -or, the two suffixes came to be used as a pair to denote the initiator and the recipient of an action.

Not to be confused with the French -ée that is a feminine noun ending (as in fiancée), which is from Latin -ata.