Easton's Bible Dictionary
Contest; wrestling; severe struggling with pain and suffering. Anguish is the reflection on evil that is already past, while agony is a struggle with evil at the time present. It is only used in the New Testament by Luke (22:44) to describe our Lord's fearful struggle in Gethsemane.
The verb from which the noun "agony" is derived is used to denote an earnest endeavour or striving, as "Strive [agonize] to enter" (Luke 13:24); "Then would my servants fight" [agonize] (John 18:36). Comp. 1 Corinthians 9:25; Colossians 1:29; 4:12; 1 Timothy 6:12; 2 Timothy 4:7, where the words "striveth," "labour," "conflict," "fight," are the renderings of the same Greek verb.
Noah Webster's New International Dictionary of the English Language
1. (n.) Violent contest or striving.
2. (n.) Pain so extreme as to cause writhing or contortions of the body, similar to those made in the athletic contests in Greece; and hence, extreme pain of mind or body; anguish; paroxysm of grief; specifically, the sufferings of Christ in the garden of Gethsemane.
3. (n.) Paroxysm of joy; keen emotion.
4. (n.) The last struggle of life; death struggle.