In ispell, ispell-american, and ispell-british, all of version 3.3.02-111.4, we
see

> grep -r -a -o -i particlar /usr/lib/ispell/*
/usr/lib/ispell/american.hash:PARTICLAR
/usr/lib/ispell/americanxlg.hash:PARTICLAR
/usr/lib/ispell/british.hash:PARTICLAR
/usr/lib/ispell/britishxlg.hash:PARTICLAR
/usr/lib/ispell/english.hash:PARTICLAR

which is simply wrong. This word is not there is Merriam-Webster's, Oxford's,
or Cambrdige's online dictionary. I suggest removing it. The correct spelling
"particular" is there AFAIK.
(Yes, some weird characters of weird computer games might be potentially called
Particlar, but this is a very, very special field.)

I don't know whether upstream exists at all, so I just report here. The
maintainer of https://lasr.cs.ucla.edu/geoff/ispell-dictionaries.html is in
"Cc", just in case you took the dictionaries from there.