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Vine's Expository Dictionary of NT Words [1]

A — 1: Γυμνάζω (Strong'S #1128 — Verb — gumnazo — goom-nad'-zo )

primarily signifies "to exercise naked" (from gumnos, "naked"); then, generally, "to exercise, to train the body or mind" (Eng., "gymnastic"),  1—Timothy 4:7 , with a view to godliness;  Hebrews 5:14 , of the senses, so as to discern good and evil;  Hebrews 12:11 , of the effect of chastening, the spiritual "exercise" producing the fruit of righteousness;  2—Peter 2:14 , of certain evil teachers with hearts "exercised in covetousness," RV.

A — 2: Ἀσκέω (Strong'S #778 — Verb — askeo — as-keh'-o )

signifies "to form by art, to adorn, to work up raw material with skill;" hence, in general, "to take pains, endeavor, exercise by training or discipline," with a view to a conscience void of offense,  Acts 24:16 .

A — 3: Ποιέω (Strong'S #4160 — Verb — poieo — poy-eh'-o )

"to do," is translated "exerciseth" in  Revelation 13:12 , said of the authority of the second "Beast." Cp. Execute See Do.

 Luke 22:25  Matthew 20:25 Mark 10:42 1—Peter 5:2

B — 1: Γυμνασία (Strong'S #1129 — Noun Feminine — gumnasia — goom-nas-ee'-ah )

primarily denotes "gymnastic exercise" (akin to A, No. 1),  1—Timothy 4:8 , where the immediate reference is probably not to mere physical training for games but to discipline of the body such as that to which the Apostle refers in  1—Corinthians 9:27 , though there may be an allusion to the practices of asceticism.

King James Dictionary [2]

EX'ERCISE, n. s as z. L. exercitium, from exerceo Eng. work.

In a general sense, any kind of work, labor or exertion of body. Hence,

1. Use practice the exertions and movements customary in the performance of business as the exercise of an art, trade, occupation, or profession. 2. Practice performance as the exercise of religion. 3. Use employment exertion as the exercise of the eyes or of the senses, or of any power of body or mind. 4. Exertion of the body, as conducive to health action motion, by labor, walking, riding, or other exertion.

The wise for cure on exercise depend.

5. Exertion of the body for amusement, or for instruction the habitual use of the limbs for acquiring an art, dexterity, or grace, as in fencing, dancing, riding or the exertion of the muscles for invigorating the body. 6. Exertion of the body and mind or faculties for improvement, as in oratory, in painting or statuary. 7. Use or practice to acquire skill preparatory practice. Military exercises consist in using arms, in motions, marches and evolutions. Naval exercise consists in the use or management of artillery, and in the evolutions of fleets. 8. Exertion of the mind application of the mental powers. 9. Task that which is appointed for one to perform. 10. Act of divine worship. 11. A lesson or example for practice.

Ex'Ercise, L exerceo.

1. In a general sense, to move to exert to cause to act, in any manner as, to exercise the body or the hands to exercise the mind, the powers of the mind, the reason or judgment. 2. To use to exert as, to exercise authority or power. 3. To use for improvement in skill as, to exercise arms. 4. To exert one's powers or strength to practice habitually as, to exercise one's self in speaking or music. 5. To practice to perform the duties of as, to exercise an office. 6. To train to use to discipline to cause to perform certain acts, as preparatory to service as, to exercise troops. 7. To task to keep employed to use efforts.

Herein do I exercise myself, to have always a conscience void of offense towards God and men.  Acts 24

8. To use to employ. 9. To busy to keep busy in action, exertion or employment. 10. To pain or afflict to give anxiety to to make uneasy.

EX'ERCISE, To use action or exertion as, to exercise for health or amusement.

Webster's Dictionary [3]

(1): ( n.) The performance of an office, a ceremony, or a religious duty.

(2): ( n.) The act of exercising; a setting in action or practicing; employment in the proper mode of activity; exertion; application; use; habitual activity; occupation, in general; practice.

(3): ( n.) Exertion for the sake of training or improvement whether physical, intellectual, or moral; practice to acquire skill, knowledge, virtue, perfectness, grace, etc.

(4): ( n.) Bodily exertion for the sake of keeping the organs and functions in a healthy state; hygienic activity; as, to take exercise on horseback.

(5): ( v. t.) To occupy the attention and effort of; to task; to tax, especially in a painful or vexatious manner; harass; to vex; to worry or make anxious; to affect; to discipline; as, exercised with pain.

(6): ( n.) That which is done for the sake of exercising, practicing, training, or promoting skill, health, mental, improvement, moral discipline, etc.; that which is assigned or prescribed for such ends; hence, a disquisition; a lesson; a task; as, military or naval exercises; musical exercises; an exercise in composition.

(7): ( n.) That which gives practice; a trial; a test.

(8): ( v. i.) To exercise one's self, as under military training; to drill; to take exercise; to use action or exertion; to practice gymnastics; as, to exercise for health or amusement.

(9): ( v. t.) To put in practice; to carry out in action; to perform the duties of; to use; to employ; to practice; as, to exercise authority; to exercise an office.

(10): ( v. t.) To set in action; to cause to act, move, or make exertion; to give employment to; to put in action habitually or constantly; to school or train; to exert repeatedly; to busy.

(11): ( v. t.) To exert for the sake of training or improvement; to practice in order to develop; hence, also, to improve by practice; to discipline, and to use or to for the purpose of training; as, to exercise arms; to exercise one's self in music; to exercise troops.

International Standard Bible Encyclopedia [4]

ek´sẽr - sı̄z ( עשׂה , ‛āsāh  ; γυμνάζω , gumnázō , ποιέω , poiéō ) : "Exercise" (meaning originally, "to drive or thrust out") has different shades of meaning: It means (1) "to do," "to put into action" ( Jeremiah 9:24 , ‛āsāh , "to do," "Yahweh who exerciseth lovingkindness";  Revelation 13:12 , poieō , "to do," "He exerciseth all the authority of the first"; Tobit 12:9, the Revised Version (British and American) "do"); (2) with violence implied, gāzal , "to take away violently," "have exercised robbery" ( Ezekiel 22:29 ); "to act habitually" ( Psalm 131:1 , hālakh , "to walk," "Neither do I exercise myself in great matters" the Revised Version, margin "walk";  Acts 24:16 , askéō , "to work up"; compare 2 Esdras 15:8; Ecclesiasticus 50:28); (3) "to train" or "discipline," gumnazō , "to use exercise," "to train up" ( 1 Timothy 4:7 , "Exercise thyself unto godliness";  Hebrews 5:14;  Hebrews 12:11;  2 Peter 2:14; compare 1 Macc 6:30; 2 Macc 15:12); (4) "to afflict" ( Ecclesiastes 1:13;  Ecclesiastes 3:10 , ‛ānāh , "to be afflicted," "exercised therewith," "exercised in it"); in  Matthew 20:25;  Mark 10:42 , katakurieúō , "to lord it over," and katexousiázō , "to exercise authority," are translated respectively "exercise dominion" and "exercise authority," the English Revised Version "lord it over" and "exercise authority"; in  Luke 22:25 , the Greek words are kurieúō , "to be lord over" and exousiázō , "to have power or authority over," the Revised Version (British and American) "have lordship," "have authority." In  1 Timothy 4:8 the noun, gumnası́a , meaning gymnastic exercise, occurs ( sōmatikḗ gumnası́a ), translated "bodily exercise," contrasted with "exercise unto godliness," the Revised Version (British and American) "For bodily exercise is profitable for a little (m "for little"); but godliness is profitable for all things," a saying to which the youth of all times would do well to give heed. In 2 Macc 4:9, Jason is said to have set up "a place of exercise" ( gumnásion ) in Jerusalem. In  1 Peter 5:2 the Revised Version (British and American), "exercising the oversight" is substituted for "taking the oversight."