Princeton's WordNet

1. ageless, aeonian, eonian, eternal, everlasting, perpetual, unending, unceasing(adj)

   continuing forever or indefinitely

   "the ageless themes of love and revenge"; "eternal truths"; "life everlasting"; "hell's perpetual fires"; "the unending bliss of heaven"

2. ceaseless, constant, incessant, never-ending, perpetual, unceasing, unremitting(adj)

   uninterrupted in time and indefinitely long continuing

   "the ceaseless thunder of surf"; "in constant pain"; "night and day we live with the incessant noise of the city"; "the never-ending search for happiness"; "the perpetual struggle to maintain standards in a democracy"; "man's unceasing warfare with drought and isolation"; "unremitting demands of hunger"

Wiktionary

1. unceasing(Adjective)

   continuous; continuing indefinitely without stopping

• sonder ophou, onophoudendAfrikaans
• غَيْر مُنْقَطِع، مُتَواصِلArabic
• непрекъснатBulgarian
• incessantePortuguese (BR)
• neustálýCzech
• unaufhörlichGerman
• uophørligDanish
• ακατάπαυστοςGreek
• incesanteSpanish
• lõputuEstonian
• بی وقفه؛ بدون توقفFarsi
• lakkaamatonFinnish
• incessantFrench
• בִּלתִי פּוֹסֵקHebrew
• लगातार, निरन्तरHindi
• neprestan, neprekinutCroatian
• szakadatlanHungarian
• terus-menerusIndonesian
• látlausIcelandic
• incessanteItalian
• 絶え間ないJapanese
• 끊임없는Korean
• nepaliaujamas, nuolatinisLithuanian
• nemitīgs; nebeidzamsLatvian
• tdk henti-hentiMalay
• onophoudelijkDutch
• uavlatelig, ustoppelig, utretteligNorwegian
• nieustającyPolish
• بی وقفه؛ بدون توقفPersian
• تل، پرله پسې، نه بس كېدونكىPashto
• contínuoPortuguese
• neîncetatRomanian
• беспрерывныйRussian
• neustálySlovak
• nenehenSlovenian
• neprekidanSerbian
• oavbruten, oupphörligSwedish
• ไม่หยุดยั้งThai
• hiç durmayan, sürekli, devamlıTurkish
• 不停的Chinese (Trad.)
• безперервний, невпиннийUkrainian
• نہ ختم ہونے والاUrdu
• liên tục , không ngừngVietnamese
• 不停的Chinese (Simp.)