From BiblePortal Wikipedia

Vine's Expository Dictionary of OT Words [1]

A. Nouns.

Mibṭâch ( מִבְטָח , Strong'S #4009), “the act of confiding; the object of confidence; the state of confidence or security.” This word occurs 15 times. The word refers to “the act of confiding” in Prov. 21:22: “A wise man scaleth the city of the mighty, and casteth down the strength of the confidence thereof.” Mibṭâch means the “object of confidence” in Job 8:14 and the “state of confidence or security” in Prov. 14:26.

Bâṭach is a noun meaning “security, trust.” One occurrence is in Isa. 32:17: “… And the effect of righteousness quietness and assurance [ bâṭach ] for ever.”

B. Verb.

Bâṭach ( בָּטַח , Strong'S #982), “to be reliant, trust, be unsuspecting.” This verb, which occurs 118 times in biblical Hebrew, has a possible Arabic cognate and a cognate in late Aramaic. The word means “to trust” in Deut. 28:52: “And he shall besiege thee in all thy gates, until thy high and fenced walls come down, wherein thou trustedst, throughout all thy land.…”

C. Adjective.

Bâṭach ( בָּטַח , Strong'S #982), “secure.” In two passages this word is used as an adjective suggesting trust and security: “And Gideon went up … and smote the host: for the host was secure [unsuspecting]” (Judg. 8:11; cf. Isa. 32:17).

D. Adverb.

Beṭach ( בֶּטַח , Strong'S #983), “securely.” The occurrences of this word appear in all periods of biblical Hebrew.

In its first occurrence beṭach emphasizes the status of a city which was certain of not being attacked: “… Two of the sons … took each man his sword, and came upon the city boldly, and slew all the males” (Gen. 34:25). Thus the city was unsuspecting regarding the impending attack. In passages such as Prov. 10:9 (cf. Prov. 1:33) beṭach emphasizes a confidence and the absence of impending doom: “He that walketh uprightly walketh surely: but he that perverteth his ways shall be known [faces certain judgment].” Israel dwells in security apart from any possible doom or danger because God keeps her completely safe (Deut. 33:12, 28; cf. 12:10). This condition is contingent on their faithfulness to God (Lev. 25:18-19). In the eschaton, however, such absence of danger is guaranteed by the Messiah’s presence (Jer. 23:5-6).

Hastings' Dictionary of the New Testament [2]

It is only in  Acts 17:9 that the word concerns us at present: ‘And when they had taken security from Jason and the rest, they let them go.’ The idiom is λαβόντες τὸ ἱκανόν and is translation of the Latin satis accipere. Cf. τὸ ἱκανὸν ποιῆσαι in  Mark 15:15, which occurs ‘as early as polybius’ (J. H. Moulton, A. Grammar of NT Greek, vol. i., ‘Prolegomena,’ 1908, p. 20 f.). It is natural to meet a Latin legal term in this Roman court; the politarchs of Thessalonica may even have used the Latin instead of the κοινή. The security demanded might be in the form either of money or of sponsors for good behaviour. It is not clear what is meant by saying that the politarchs ‘let them go.’ It is uncertain also whether the security was for the ‘good behaviour’ of Jason and the rest, for the production of St. Paul and Silas before the politarchs, or for the ‘good behaviour’ of St. Paul and Silas (cf. R. J. Knowling, Expositor’s Greek Testament, ‘Acts,’ 1900, in loco.). F. Blass (Acta Apostolorum, 1895, in loco) considers the phrase a commercial, not a legal, term. In any case, ‘the brethren immediately sent away Paul and Silas by night unto BerCEa’ ( Acts 17:10). The haste and the cover of darkness indicate the urgency of the predicament, which concerned, apparently, the welfare not merely of St. Paul and Silas, but also of Jason and the rest, because of ‘the security’ given to the politarchs. It is not open to make a charge of cowardice here against either Jason or St. Paul. It was a practical question of how to meet an emergency due to jealousy and prejudice.

A. T. Robertson.

Vine's Expository Dictionary of NT Words [3]

1: Ἱκανός (Strong'S #2425 — Adjective — hikanos — hik-an-os' )

"sufficient," is used in its neuter form with the article, as a noun, in  Acts 17:9 , "(when they had taken) security," i.e., satisfaction, lit., "the sufficient." The use of hikanos in this construction is a Latinism in Greek. See Moulton, Proleg., p. 20. Probably the bond given to the authorities by Jason and his friends included an undertaking that Paul would not return to Thessalonica. Any efforts to have the bond cancelled were unsuccessful; hence the reference to the hindrance by Satan ( 1—Thessalonians 2:18 ). See Able , C, No. 2.

Webster's Dictionary [4]

(1): ( n.) The condition or quality of being secure; secureness.

(2): ( n.) Freedom from apprehension, anxiety, or care; confidence of power of safety; hence, assurance; certainty.

(3): ( n.) Freedom from risk; safety.

(4): ( n.) That which secures or makes safe; protection; guard; defense.

(5): ( n.) One who becomes surety for another, or engages himself for the performance of another's obligation.

(6): ( n.) Something given, deposited, or pledged, to make certain the fulfillment of an obligation, the performance of a contract, the payment of a debt, or the like; surety; pledge.

(7): ( n.) Hence, carelessness; negligence; heedlessness.

(8): ( n.) An evidence of debt or of property, as a bond, a certificate of stock, etc.; as, government securities.

King James Dictionary [5]

SECU'RITY, n. L. securitas.

1. Protection effectual defense or saftey from danger of any kind as a chain of forts erected for the security of the frontiers. 2. That which protects or guards from danger. A navy constitutes the security of Great Britain from invasion. 3. Freedom from fear or apprehension confidence of safety whence, negligence in providing means of defense. Security is dangerous, for it exposes men to attack when unprepared. Security in sin is the worst condition of the sinner. 4. Safety certainty. We have no security for peace with Algiers, but the dread of our navy. 5. Anything given or deposited to secure the payment of a debt, or the performance of a contract as a bond with surety, a mortgage, the indorsement of a responsible man, a pledge, &c. 6. Something given or done to secure peace or good behavior. Violent and dangerous men are obliged to give security for their good behavior, or for keeping the peace. This security

in being bound with one or more sureties in a recognizance to the king or state.