Jamieson, Fausset and Brown on Revelation 21:8

8. the fearful--Greek, "the cowardly," who do not quit themselves like men so as to "overcome" in the good fight; who have the spirit of slavish "fear," not love, towards God; and who through fear of man are not bold for God, or "draw back." Compare Re 21:27; 22:15.

unbelieving--Greek, "faithless."

abominable--who have drank of the harlot's "cup of abominations."

sorcerers--one of the characteristics of Antichrist's time.

all liars--Greek, "all the liars": or else "all who are liars"; compare 1Ti 4:1, 2, where similarly lying and dealings with spirits and demons, are joined together as features of "the latter times."

second death--Re 20:14: "everlasting destruction," 2Th 1:9; Mr 9:44, 46, 48, "Where THEIR worm dieth not, and the fire is not quenched."