Istar noun "Wizard", used of Gandalf, Saruman, Radagast etc. Pl. Istari is attested. Gen. pl. in the phrase Heren Istarion "Order of Wizards" (UT:388). "The istari are translated wizards because of the connexion of wizard with wise and so with witting and knowing" (Letters:207); by this translation Tolkien tries to reproduce the relationship between Quenya istar and ista- #1, 2.
Quenya
sairon
wizard
Istar
wizard
curuvar
wizard
curuvar _("k")_noun "wizard" (LT1:269 but Gandalf, Saruman etc. were istari)
sairon noun "wizard" (SAY); according to LT2:337 and GL:29, Sairon is also the Quenya (or Qenya) name of Dairon (Daeron).