|Noah Webster's Dictionary|
1. (a.) Apt to forget; easily losing remembrance; as, a forgetful man should use helps to strengthen his memory.
2. (a.) Heedless; careless; neglectful; inattentive.
3. (a.) Causing to forget; inducing oblivion; oblivious.
Int. Standard Bible Encyclopedia
for-get', for-get'-ful (shakhach; epilanthanomai):
"Forget" is to fail to hold in mind, and the forgetfulness may be either innocent or blameworthy. In the Old Testament the word is most frequently used as translation of shakhach in a blameworthy sense: to forget the covenant, the law, Yahweh their God (Deuteronomy 4:9, 23, 11; Deuteronomy 6:12 Judges 3:7 1 Samuel 12:9 Psalm 44:20, etc.). In an innocent or neutral, sometimes good, sense it is used in Genesis 27:45 Deuteronomy 24:19 Job 9:27; Job 11:16; Job 24:20 Psalm 102:4, etc. It is also used of God forgetting or not seeming to care (Psalm 9:12; Psalm 10:11, 12; 13:01; 42:09:00; 77:9 Isaiah 49:15, etc.). To "forget" sometimes means to forsake (Psalm 45:10; Psalm 74:19, etc.).
In the New Testament epilanthanomai is used of simple forgetting (Matthew 16:5 Mark 8:14, etc.; in Luke 12:6 the sense of care is implied); Philippians 3:13, "forgetting the things which are behind," has the force of leaving behind. "Forgetful" in James 1:25 is epilesmone, the Revised Version (British and American) "a hearer that forgetteth." "Forgetfulness" Psalm 88:12, "the land of forgetfulness," is a synonym for Sheol, where all forget and are forgotten. the Revised Version (British and American) has "forget not" for "be ignorant of" (2 Peter 3:8; similarly 2 Peter 3:5).
W. L. Walker
Forgetful (4 Occurrences)
Hebrews 13:2 Be not forgetful to entertain strangers: for thereby some have entertained angels unawares. (KJV DBY WBS YLT)
Hebrews 13:16 But of doing good and communicating of your substance be not forgetful, for with such sacrifices God is well pleased. (DBY YLT)
James 1:25 But whoso looketh into the perfect law of liberty, and continueth therein, he being not a forgetful hearer, but a doer of the work, this man shall be blessed in his deed. (KJV DBY WBS YLT NAS)
2 Peter 1:9 for he with whom these things are not present is blind, dim-sighted, having become forgetful of the cleansing of his old sins; (YLT)