1. A thin, usually spherical or hemispherical film of liquid filled with air or gas.
2. A globular body of air or gas formed within a liquid: air bubbles rising to the surface.
3. A pocket formed in a solid by air or gas that is trapped, as during cooling or hardening.
4. a. The act or process of forming bubbles.
b. A sound made by or as if by the forming and bursting of bubbles.
5. Something insubstantial, groundless, or ephemeral, especially:
a. A fantastic or impracticable idea or belief; an illusion.
b. A speculative scheme that comes to nothing.
6. Something light or effervescent.
7. A usually transparent glass or plastic dome.
8. A protective, often isolating envelope or cover.
In the dark
I stumble for purchase
To all but the owls.
It never stopped me.
Bubble picture extracted from LIFE archive.