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I have a lot of friends with the same name as me, but we're all different.
There are many "lights," red, blue, ultraviolet, green.
I love to swim and dive.
Many maritime vehicles, such as boats and submarines, have a green, white and red light affixed to the hull for navigation purposes. Also, traffic lights hanging from a line in the wind may "swim" or "dive."
You might find me at a ball game, at a festival, or lying down outside.
Stadium lights, festival lights, lawn lights
I changed my name when I became old.
Lights used to be known as "lamps." (I'm stretching here, maybe)
I run on the edge of a diamond
Baseball runners run on the edge of a baseball diamond, and are sometimes given the "green light" to proceed to the next base.
and hold court outside
Traffic lights have authority to make cars stop, yield, or pass freely, judging them in "traffic intersection court." :)
"I light the light and now my room is very light" verb, noun, adjective
I wouldn't say that lights are "usually" green, but there certainly are lots of green lights around: Traffic lights all have a green phase, green LEDs, metaphorically giving the "green light," etc. etc. Also, in current times, most of the lights that you buy are energy efficient, or green.