uncommon
rare
non-English
semirare
geason
rareish
rare as rocking horse shit
Alwin
unique
Isom
rare as a four-leaf clover
Englishy
superrare
unlikelily
inexpressable
different
caseless
slip of the tongue
supersubtle
caselessness
rarer than hens' teeth
Shakespeare
noneven
vaguity
impostor
amphibological
rare as hen's teeth
peculiar
seldomness
ultrarare
semiobscure
unclearly
out of the way
seldomly
nonvernacular
pauciloquently
scarce
noncommonable
unvernacular
one in a million
subobscure
uncommonable
rarely
unoften
miscegenistic
miscegenative
strictly
antrin
miscegenic
remarkable