|Easton's Bible Dictionary|
Occurs in Authorized Version, James 5:16. The Revised Version renders appropriately: "The supplication of a righteous man availeth much in its working", i.e., "it moves the hand of Him who moves the world."
Noah Webster's Dictionary
(a.) Adequate; sufficient to produce a desired effect; as, an effectual writing method; efficient; operative; decisive.
Int. Standard Bible Encyclopedia
In the Old Testament, the Revised Version (British and American) renders "fulfilment" for "effect" in Ezekiel 12:23 (Hebrew dabhar, "matter"); and in Jeremiah 48:30 "His boastings have wrought nothing" for the vaguer "His lies shall not so effect" of the King James Version. In the King James Version of the New Testament, "make of none effect" occurs repeatedly: as the translation of Greek akuroo, "render void" (Matthew 15:6 Mark 7:13); of katargeo, "annul" (Romans 3:3 (the King James Version "make without effect"); Romans 4:14 Galatians 3:17); and of kenoo, "make empty" (1 Corinthians 1:17). the Revised Version (British and American) renders "make of none effect" in Romans 3:3 Galatians 3:17; "make void" in the other cases, with no apparent reason for the lack of uniformity. Greek energeo is the opposite in meaning of katargeo above. Its derivative energes, "effective," is rendered "effectual" by English Versions of the Bible in 1 Corinthians 16:9 Philemon 1:6. the Revised Version (British and American) dispenses with "effectual," "effectually," in the other cases where the King James Version has used these words as auxiliary in the translation of energeo or of energeia, "working" (2 Corinthians 1:6 Galatians 2:8 Ephesians 3:7; Ephesians 4:16 1 Thessalonians 2:13 James 5:16).
F. K. Farr
Effectual (8 Occurrences)
1 Corinthians 16:9 For a great door and effectual is opened unto me, and there are many adversaries. (KJV ASV DBY WBS YLT)
2 Corinthians 1:6 And whether we be afflicted, it is for your consolation and salvation, which is effectual in the enduring of the same sufferings which we also suffer: or whether we be comforted, it is for your consolation and salvation. (KJV WBS)
Ephesians 3:7 Whereof I was made a minister, according to the gift of the grace of God given unto me by the effectual working of his power. (KJV WBS)
Ephesians 4:16 From whom the whole body fitly joined together and compacted by that which every joint supplieth, according to the effectual working in the measure of every part, maketh increase of the body unto the edifying of itself in love. (KJV WBS)
Philemon 1:6 That the communication of thy faith may become effectual by the acknowledging of every good thing which is in you in Christ Jesus. (KJV ASV WBS)
James 1:25 But he who goes on looking into the true law which makes him free, being not a hearer without memory but a doer putting it into effect, this man will have a blessing on his acts. (See NAS)
James 5:16 Confess your faults one to another, and pray one for another, that ye may be healed. The effectual fervent prayer of a righteous man availeth much. (KJV WBS)
Job 12:16 With him is strength and effectual knowledge; the deceived and the deceiver are his. (DBY)