Outstanding and optimistic are positive words. They begin with the letter o.
overpowering
It depends on the meaning you're using for the word "caring." Two words that fit are: Objecting (caring; having an opinion) Overseeing (caring; tending to)
keep an eye on
Orbit and ozone are space words. They begin with the letter o.
agoallegroalsoaltoarmadilloaudio
organicosmosisoxygen
omnipotent
· osmosis
Obese and oddball are insulting words. They begin with the letter o.
Capable, caring, classy, courteous and cultured are positive words. They begin with the letter C.
ocean