usageaster
/ˌjuːsɪdʒˈastə/ /ˈjuːsɪdʒastə/ /ˌjuːsɪdʒˈeɪstə/originally US
noun
A self-appointed expert on language usage, especially one regarded as having ill-informed, conservative, or pedantic views.
Origin
1980s; earliest use found in Tom Clark (b. 1941). From usage + -aster, after poetaster.