the.com/fluid

Matter that gave up having opinions about its shape.

means A substance — liquid or gas — that flows and takes the shape of whatever contains it, rather than holding a fixed form of its own.

from From Latin fluidus, 'flowing,' built from fluere, 'to flow' — the same root that gave English effluent, fluent, and influence (originally the idea of an unseen fluid 'flowing in' from the stars to shape events). English picked up 'fluid' in the 1600s, first in scientific and medical writing, to describe anything that moved and merged rather than stayed put.

physics definition
Anything that deforms continuously under shear stress
plasma too
Some scientists count plasma as a fourth fluid state
identity sense
First used for flexible identity or categories around the 1980s-90s
glass surprise
Glass is technically a solid, not a slow-moving fluid
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