For pronunciation and definitions of きう – see the following entry.
[noun] sphere, globe, orb
[noun] (baseball) pitch
[noun] (slang, electronics) vacuum tube, valve
(This term, きう, is a historical hiragana spelling of the above Sino-Japanese term.
For a list of all kanji read as きう, not just those used in Japanese terms, see Category:Japanese kanji read as きう.)