Is "by extension" the same as "figuratively" when talking about meanings of words?
light bulb (plural light bulbs)
1.An evacuated glass bulb containing a metal filament which is heated by electrical resistance to produce light.
2.(by extension) An article that resembles such a bulb and converts electricity to light by any process. an incandescent light bulb a fluorescent light bulb an LED light bulb
3.(figuratively) Used in reference to the sudden arrival of a realization, an inspiration, an idea, or the like.
Thank you in advance!