This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

adj. Being or seeming to be without an end or limit; boundless: an endless universe; an endless conversation.

adj. Formed with the ends joined; continuous: an endless chain.

adj. having no end

adj. extending indefinitely

adj. Without end; having no end or conclusion; perpetual; interminable; -- applied to length, and to duration

adj. Infinite; excessive; unlimited.

adj. Without profitable end; fruitless; unsatisfying.

adj. Void of design; objectless.

adj. having a linear or ribbonlike form with the two ends connected together, such as in a circle, ellipse, torus, or any other closed loop. Belts or chains used in drive mechanisms are considered endless in this sense. See endless chain.

Not having a termination; continuing without end, really or apparently; having no limit or conclusion: as, endless progression; endless bliss; the endless pursuit of an object.

Not having ends; returning upon itself so as to exhibit neither beginning nor end: as, an endless belt or chain; a circular race-course is endless.

Perpetually recurring; interminable; incessant; continual: as, endless praise; endless clamor.

Without object, purpose, or use.

Without profitable conclusion; fruitless.

Synonyms Eternal, everlasting, perpetual, unceasing, imperishable, uninterrupted, boundless, immeasurable, unlimited.

adj. infinitely great in number

adj. having the ends united so as to form a continuous whole

adj. having no known beginning and presumably no end

adj. tiresomely long; seemingly without end

"It is used, in a few instances, to denote an endless age, by attaching to it another word for _endless_."

infinite    continuous    uninterrupted    long   

finite   

immortal    constant    purposeless    endless belt    endless screw    endless saw   

endlessly    endlessness   

unceasing    undying    perpetual    boundless    uninterrupted    unlimited    everlasting    unending    infinite    continual   

trendless   

vast    terrible    eternal    constant    long    interminable