Bible Dictionaries
Angel

Vine's Expository Dictionary of NT Words

"a messenger" (from angello, "to deliver a message"), sent whether by God or by man or by Satan, "is also used of a guardian or representative in Revelation 1:20 , cp. Matthew 18:10; Acts 12:15 (where it is better understood as = 'ghost'), superior to man, Hebrews 2:7; Psalm 8:5 , belonging to Heaven, Matthew 24:36; Mark 12:25 , and to God, Luke 12:8 , and engaged in His service, Psalm 103:20 . "Angels" are spirits, Hebrews 1:14 , i.e., they have not material bodies as men have; they are either human in form, or can assume the human form when necessary, cp. Luke 24:4 , with Luke 24:23 , Acts 10:3 with Acts 10:30 .

"They are called 'holy' in Mark 8:38 , and 'elect,' 1 Timothy 5:21 , in contrast with some of their original number, Matthew 25:41 , who 'sinned,' 2 Peter 2:4 , 'left their proper habitation,' Jude 1:6 , oiketerion, a word which occurs again, in the NT, only in 2 Corinthians 5:2 . Angels are always spoken of in the masculine gender, the feminine form of the word does not occur."* [* From Notes on Thessalonians, by Hogg and Vine, p. 229.]

Note: Isangelos, "equal to the angels," occurs in Luke 20:36 .