Who was the first Ḥiloni?
In modern Hebrew the word חילוני, ḥiloni, is used to describe someone who isn’t religious. Some people prefer the word חופשי, ḥofshi, since it expresses something positive, that someone is “free,” while ḥiloni is from the root חלל, “profane” or “violate.” I always thought that the word ḥiloni was fairly modern, but it turns out that it is actually found in Midrash Va-Yikrah Rabbah, chap. 24:7.
R. Judan said in the name of R. Samuel b. Nahman: It may be compared to the case of a king who had an undergarment and used to bid his servant: ‘Shake it out and fold it,’ etc. R. Samuel b. Nahman said: It may be compared to the case of a High Priest who was walking on the road and met a layman who said to him: ‘ I will walk with you.’ He answered him: ‘My son! I am a priest and am going along a ritually clean road. It is not the proper way for me to walk among graves. If you will come with me, well and good; but if not I shall eventually have to leave you and go my way!’
According to this midrash, a ḥiloni is a non-priest. The term is also found in some of the Aramaic translations of the bible and a number of scholars have discussed the possible Aramaic origins of this word. See here for a discussion of the word and its etymology.
Update: Reader YG pointed out to me the peculiar phrase in the Hebrew, “כהן גיבור” (“a heroic priest”) instead of what one would expect, “כהן גדול” (“a High Priest”). The peculiar phrase “כהן גיבור” is found in most of the MSS and the Arukh, while “כהן גדול” is found in the printed editions. The English translation is from Soncino which is based upon the printed edition, hence the translation is “a High Priest.” Margulies, in his edition of Va-Yikra Rabbah, says that the phrase “כהן גיבור” is the original version, having been changed to the more recognizable “כהן גדול”. For one who accepts “כהן גיבור” as the original reading, this is a case of lectio difficilior, that the more difficult reading is the more authentic one.