Answer:
I am partially baked. I am not completely lit. I am a portion of the moon. I am lesser than full wit. I am a divider of the hour. I am not a total lie. I am a sibling through one parent.
A sport with love and service played by singles and pairs.
I am the key that is the hardest to turn
I am used when you jump off a bridge for fun.
Some will use me, others not. Some have remembered, others forgot. For profit or gain, I'm used expertly. I can't be picked off the ground or tossed into the sea. What am I?
All about, but cannot be seen, Can be captured, cannot be held, No throat, but can be heard. Who am I?