Lexical Definition

‎τήρησις‎ tḗrēsis (tay'-ray-sis) jail/keeping G:N-F
from ‎τηρέω‎

hold.

Usage: 3 forms in 3 verses
Form Translated As     In Verse(s)
τηρήσει jail Acts.5.18
τήρησισ keeping 1Cor.7.19
τήρησιν custody Acts.4.3

Abbott-Smith

** τήρησις, -εως, ἡ (< τηρέω), [in LXX: Wi 6:18, (Si 35 (32):23), I Mac 5:18, II Mac 3:40, III Mac 5:44 * ;]
1. a watching, hence, imprisonment, ward (v. Deiss., BS, 267): Ac 4:3 5:18.
2. a keeping: τ. ἐντολῶν (cf. Sir, Wi, ll. c., and v. Westc. on I Jo 2:3.), I Co 7:19.†

Abbott-Smith References

Book Refs
Acts 4:3 · 5:18
1 Corinthians 7:19
1 John 2:3

Liddell-Scott-Jones

τήρησις-ησις, εως, ,

watching, safe-keeping, guarding, ἀφύλακτος τ. [Refs 5th c.BC+]; τῆς οἰκίας [Refs 3rd c.AD+]; ἀξιώματος [Refs 5th c.BC+]; [πλούτου] [Refs 1st c.BC+]; preservation, e.g. of health, [Refs 2nd c.AD+]; observance, νόμων, ἐντολῶν, [τήρησιςησιν τοῦ ὕδατος “SIG” 683.60 (Olympia, 2nd c.BC). ">LXX+NT+2nd c.BC+]

__2 vigilance, [Refs 5th c.BC+]
__3 means of keeping or guarding, τὰς λιθοτομίας.., ἀσφαλεστάτην τ. the quarries.., the most secure place of custody, [NT+5th c.BC+]
__II observing, observation, τῶν καθόλου συμβαινόντων (as Empiric term) [Refs 2nd c.AD+]

LSJ Scripture Refs: 1Cor.7.19Acts.4.3