Adelphous IV was the fourth planet in the Adelphous system which sustained a population prior to 2381.

The USS Enterprise was headed for this world in 2367 when Data relieved Worf of command at the beginning of the night shift. (TNG episode: "Data's Day")

During the Borg Invasion of 2381, over seven thousand Borg cubes launched a simultaneous attack on the Alpha and Beta Quadrants from the Azure Nebula; Adelphous IV was one of the planets attacked and its population wiped out. (ST - Destiny novel: Mere Mortals)

Startrek.com spells the planet as Adelphus IV.

Planets visited by the USS Enterprise-D
2364	Earth • Deneb IV • Archaria III • Ligon II • Styris IV • Omicron Theta • Gamma Tauri IV • Delphi Ardu IV • Peacekeepers' World • Parliament • Rubicun III • Quadra Sigma III • Haven • Torona IV • Angel I • Starbase 74 planet • Bynaus • Tigan VII • Syntagus Theluv • Tarod IX • Faltos • Persephone V • Mordan IV • Aldea • Velara III • Relva VII • Minos • Brentis VI • Treva • Vagra II • Ornara • Brekka • Vandor IV • Sarona VIII • Dytallix B
2365	'aucdet IX • Tenara • Epsilon Miranda V • DQN 1196 • Raimon • Feenix-Denn IV • Himalias V • Thiopa • Gravesworld • Ramatis III • Solais V • Gagarin IV • Elysia • Iconia • Pacifica • Bringloid V • Mariposa • Drema IV
2366	Kavis Alpha IV • Tau Cygna V • Galorndon Core • Acamar III • Orelious IX • Bre'el IV • Cassiopeia Delta VII • Archer IV • Betazed • Vulcan • Rutia IV • Jouret IV
2367	Saturn • Earth • Turkana IV • Camus II • Tagus III • Adelphous IV • Evadne IV • Qo'noS
2368	Qo'noS • El-Adrel IV • Valo I • Valo II • Qualor II • Vulcan • Galorndon Core • Hermeticus II • Votar VII • Sindar • Tessen III • Rajatha Prime • Earth
2369	Frigis • Hobson Delta II • Bajor • Eloh • Riat • Atrea IV • Nervala IV • Enoch VII • Earth
2370	Terrellian crashsite world • Marijne VII • K'Trall • Dessica II • Barradas III • Calder II • Vulcan • Kesprytt III • Enoch VII • Dyson Sphere • Hera • Atrea IV • Vacca VI • Dorvan V • Hera • Krantin • Syng II • Earth
2371	Sindikash • Thanet • Ntignano • Damiano • Veridian III