I was recently discussing the prohibition of studying "shitrei hedyotot" (loosely translated as secular studies). But when looking at a debate of the Rabbis in Talmud Bavli Sanhedrin 21:b-22:a the word hedyotot is there but it's referring to Samaritans, who are definitely not secular. So what does hedyotot actually mean? Is it a derogatory word?
Rashi (Shabbat 116b s.v. shtar hedyotot) describes it as page of [business] calculations or a letter regarding a lost item:
שטר הדיוטות - כגון של חשבונות, או איגרות השלוחות למצא חפץ.
Elsewhere (Shabbat 149a) he describes it as business documents:
כל הני - שמא יקרא בשטרי הדיוטות של מקח וממכר קאמר.
The Yerushalmi Megillah (3:4) apparently understood it to even include Scripture (cf. Tosefta Kifshuttah to Shabbat (13:2-3 p. 202)).
Jastrow writes that the etymology of "הדיוט" is from the Greek ἰδιώτης (person lacking professional skill, a private citizen, individual) the precursor of the English word idiot.
He defines it as:
commoner, ignoble, ignorant
He also notes that it can refer to Samaritans (presumably in contradistinction to Pharisees).
Evidently, the term can have a range of meanings depending on context (see the Jastrow entry below for some examples.)
I always was under the impression that it means, ordinary or regular.
Like we have a Kohein Gadol, and a Kohein Hedyot.
See for example how it is translated here, in the Oxford Dictionary of the Jewish Religion.