Boundless

adj.hopeful, energeticliterary

What it means

So great in amount or reach that no practical limit is apparent.

Reach for it when giving emphatic praise to abundant energy, love, curiosity, or possibility

Her boundless curiosity turned every delay into a chance to learn.

everyday
endless
when duration or repeated supply seems never to stop
not when Endless may sound weary or negative, unlike enthusiastic boundless.
everyday
limitless
when the absence of a limit should be stated plainly
not when Limitless can make a factual claim where boundless reads as warm emphasis.
warm
unfailing
when reliability across time is more important than amount
not when Unfailing support may be modest; boundless support suggests abundance.
professional
abundant
when plenty is enough and exaggeration should be avoided
not when Abundant acknowledges a large supply without claiming that limits disappear.
formal
inexhaustible
when use does not seem to reduce the supply
not when It suits energy and resources better than affection with emotional breadth.
formal
infinite
when a literally mathematical or grand philosophical scale fits
not when Ordinary human patience is rarely infinite, so the word can sound careless.
literary
immeasurable
when the quantity cannot be adequately assessed
not when Something measurable but very large can still be described as boundless figuratively.
literary
vast
when breadth or extent, rather than supply, creates the impression
not when Vast knowledge concerns range; boundless curiosity concerns an apparently unlimited impulse.

boundless energy
The children's boundless energy carried the rehearsal through a long afternoon.
boundless enthusiasm
His boundless enthusiasm drew hesitant neighbors into the project.
boundless possibilities
The blank workshop offered boundless possibilities to the young inventors.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.