Misc: on what was pennsylvania incorrectly spelled?

Questions

in ancient greece, what was a myriad?

in arabian mythology, what is the spirit of a murdered man seeking to avenge his death?

in art, a form of watercolor that uses opaque pigments rather than the usual transparent watercolor pigments?

in astronomy, the apparent great-circle annual path of the sun in the celestial sphere, as seen from the earth?

in badminton, how many points win a singles game?