You can suggest a new alias, but they must be approved by an administrator before they are activated.
An example of how to use this: (Neon_Genesis_Evangelion is the tag and Evangelion is the alias. Evangelion -> Neon_Genesis_Evangelion)

Alias To Reason
mouth_open (0) open_mouth (48762) Same
giggling (0) laughing (316) Some users have been tagging giggling instead of laughing lately, might be easier to search for.
chain (0) chains (1279) As of writing, plural is more than 7 times as popular
cum_in_hair (0) cum_on_hair (703)
bare_feet (0) barefoot (12474)
pigtails (0) twintails (11105)
pig_tails (0) twintails (11105)
umimi_habara (0) brooke_walker (1) Same
body_suit (0) bodysuit (7065) Same
re_zero (0) re:zero_starting_life_in_another_world (204) two tags that are seperate
human_pet (0) pet_play (4893) Same
yuzu_hiragi (0) zuzu_boyle (52) same character
big_breasts (0) large_breasts (59648) Same
pepper_pots (0) pepper_potts (14) Mispelling of character name
pedrovin (0) vincios (0) Same artist, just uses two different usernames.
nihilego (0) ub-01 (128) real name
rem (0) rem_(re:zero) (83) Standardized tag for one-word names.
re:zero (0) re:zero_starting_life_in_another_world (204) same
gym_clothes (0) gym_uniform (487) same
egg (0) eggs (241) Same
facesitting (0) sitting_on_face (224) Proper tag form
face_sitting (0) sitting_on_face (224) Proper tag form
romantic (0) consensual (1491) Were tied together in the original pool "Consensual/Romantic MC"; makes them easier to find through tags.
momonga (0) ainz_ooal_gown (2) Alias
ambiguous_gender (0) androgynous (2042) Same
utakata_(artist) (0) utakata0824 (1)
bermasin (0) ber00 (11) bermasin - artist's real name ber00 - artist's nom de guerre since the artist chooses to represent themselves with a chosen na
mismatched_eyes (0) heterochromia (826) Both of them mean the same thing: left and right eyes differing in color.
raffine (0) raffina (16) Romanization changed officially from Puyo Pop Fever to Puyo Puyo Tetris
ych (0) your_character_here (46) YCH is a common abbreviation in the art world.
akuma_no_riddle (0) riddle_story_of_devil (3) English name
pocketwatch (0) pocket_watch (1712) Alternate spelling
chewycuticle! (0) chewycuticle (15)
scott_summers (0) cyclops_(x-men) (21) Same character; don't mind which way round it aliases
grenda (0) grenda_grendinator (7) full name of character
nsfw-dealer (0) silent-sid (1) literal additional alias
doris_(meet_the_robinsons) (0) dor_15 (11) properly spelled as per the movie [although doris is how it is pronounced], as well as a much shorter, simpler tag
torn_clothing (0) torn_clothes (4047) Same.
cat_suit (0) catsuit (302) they're the same thing, different spelling.
maxlat (0) maxtlat (8) I think I missed the T; the 2nd spelling seems to be the correct one
janna_(star_vs._the_forces_of_evil)_star_butterfly (0) janna_ordonia (15) older tag is longer, less precise, not in hypnohub style given we now have a last name
aqua (0) aqua_(kingdom_hearts) (290) Other characters named Aqua exist, e.g. from Konosuba. Rules say that single-word names must be appended with the series or auth
homura_(xenoblade_chronicles_2) (0) pyra_(xenoblade) (329) Same character, just the Japanese vs Western name.
swim_suit (0) swimsuit (3051) the 2nd is the more popular tag
gojiro7 (0) shadow2007x (89) shadow2007x seems to also be Kojiro7 on pixiv and Gojiro7 on furaffinity
masaki195 (0) johnni_kun (1) Masaki195 = hentai foundry johnni kun = tumblr
tiara (0) crown (2611) crown is a larger tag and a more general tag that covers the more narrow tiara tag
ballgag (0) ball_gag (813) Alternate spelling.
flowers (0) flower (809) Danbooru does this.
large_cock (0) large_penis (1119) Currently both are used interchangeably; Danbooru, etc. use large_penis so let's do that.