Extended Strong's Greek Lexicon (Abbott-Smith based)
prison/watch: prison
Usage: φυλακή, -ῆς, ἡ (φυλάσσω) [in LXX chiefly for מִשְׁמֶרֶת and cogn. forms, also for כֶּלֶא etc. ;] __(a) actively, a guarding, guard, watch (Hom., Plat., Xen., al.): cogn. accusative, φυλάσσειν φυλακάς, to keep watch, Luk.2:8; __(b) of those who keep watch (as also Lat. custodia), a guard; pl., sentinels, a guard (Hom., al.): Act.12:10; __(with) of the place where persons are kept under guard, a prison (Hdt., Thuc., al.): Mat.14:10, Mrk.6:17, Luk.3:20, Act.5:19, 2Co.6:5, 1Pe.3:19, Rev.18:2, al.;
__(d) of the time during which guard was kept by night (Lest. vigilia; Anthol.), a watch: Mat.14:25 24:43, Mrk.6:48, Luk.12:38 (AS)