an approximate calculation of quantity or degree or worth
"an estimate of what it would cost"
"a rough idea how long it would take"
(music) melodic subject of a musical composition
"the theme is announced in the first measures"
"the accompanist picked up the idea and elaborated it"
An abstract archetype of a given thing, compared to which real-life examples are seen as imperfect approximations; pure essence, as opposed to actual examples.
"After years of studying countless sculptures, he finally understood that his teacher was referring to the ideal form rather than any single physical statue they could point to."
In plain English: An idea is a thought or plan that forms in your mind about something you want to do or create.
"I had a sudden idea to bake cookies for the party."
Usage: Use "idea" in daily conversation to refer to a thought, plan, or suggestion rather than a philosophical concept or perfect form. Avoid using it when you mean the abstract essence of something, as that is a specialized meaning not found in ordinary speech.
The word idea comes from the Latin idea, which originally meant a Platonic archetype or notion. This Latin term was borrowed from Ancient Greek ideas that ultimately trace back to a Proto-Indo-European root meaning "to see" or "to know."