From Middle English ever-lasting (“(adjective) eternal, perpetual; constant; (adverb) eternally; (noun) eternity”), from ever (“at all times, always, constantly; eternally, perpetually; regularly; etc.”) + lasting (“continuing, lasting; eternal; etc.”). * Ever is derived from Old English ǣfre (“ever”), possibly from ā (“always, ever”) + in fēore (“in life”). Ā is from Proto-West Germanic *aiw (“eternity; long time”), from Proto-Germanic *aiwaz (“long time; eternity”), ultimately from Proto-Indo-European *h₂ey- (“life, vital force; long time; eternity”); and fēore is the dative singular of feorh (“life”), from Proto-West Germanic *ferh (“life; kind of tree”), from Proto-Germanic *ferhwą (“body; life; tree”), probably ultimately from Proto-Indo-European *perkʷ- (“oak tree”) (as the oak represented life and vitality in Germanic mythology). * Lasting is derived from lasten (“to continue, last; etc.”) + -ing (suffix forming present participle forms of verbs, often used as adjectives)); and lasten from Old English lǣstan (“to follow, pursue; to carry out, perform”), from Proto-West Germanic *laistijan (“to follow, pursue; to carry out, perform”), from Proto-Germanic *laistijaną (“to follow, pursue”), ultimately from Proto-Indo-European *leys- (“to trace, track”). By surface analysis, ever (adverb) + lasting (adjective).

sempiternal • aeonian • ageless • Arrant • complete • constant • consummate • continuate • double-dyed • dreich • eonian • eternal • everlasting flower • Gross • heavenly • incessive • infinite • lasting • perennial • perfect • permanent • perpetual • perpetuate • pure • sodding • Staring • Stark • still • thoroughgoing • unadulterated • unceasing • unending • unlimited • Utter