light from nonthermal sources
"The ancient phosphorescent stone continued to glow in the dark long after the fire had gone out, emitting a soft light without any heat."
the phenomenon of light emission by a body as its temperature is raised
"The metal bar began to glow bright orange as it was heated in the fire."
a steady even light without flames
"The embers in the fireplace continued to glow long after the fire had died down."
The state of a glowing object.
"The soft glow from the fireplace warmed the room as night fell."
In plain English: A glow is a soft, steady light that seems to come from something itself rather than reflecting another source.
"The glow from the neon sign illuminated his face in the dark alley."
emit a steady even light without flames
"The fireflies were glowing and flying about in the garden"
To give off light from heat or to emit light as if heated.
"The metal bar began to glow red hot after being left in the furnace."
In plain English: To glow means to give off light softly and steadily, often without burning hotly.
"The candle flame began to glow after I blew out all the other lights in the room."
Usage: Use glow when describing an object emitting soft, steady light due to heat or internal energy rather than burning brightly like a flame. This verb often implies a warm radiance that can also metaphorically describe a person's happy appearance.
The word glow comes from Middle English glouen, which originally described objects giving off heat and light without a visible flame. Over time, this term traveled into modern usage to cover both literal shining brightness and figurative expressions of intense emotion or flushed skin.