Final answer:
An implied comparison between two ideas without using 'like' or 'as' is known as a metaphor.
Step-by-step explanation:
An implied comparison between two ideas that is conveyed by the abstract meaning contained in the words used to make the comparison is known as a metaphor. Unlike a simile, which explicitly uses words like 'like' or 'as' to draw similarities, a metaphor implies the comparison directly. For example, saying 'Hope is the thing with feathers' (Emily Dickinson, "Hope") is a metaphor because it describes hope as being similar to a bird with feathers, without using 'like' or 'as'.