time
month
חדש · ירח · ירח
Bottom line
Both words come out month in English, but they name different things. Chodesh is properly the new moon, the month's beginning, from chadash, "new"; "month" is a secondary, borrowed sense (Malbim, Rav Hirsch). Yerach the column takes, as a suggestion and not a ruling, to be the month as a full span of days, kin to yareach, the moon; Malbim himself reads it as simply a thirty-day period. Where a pasuk uses chodesh in a place that calls for Rosh Chodesh, render "new moon," not "month." Practically: by custom a kesubah says chodesh and a get says yerach (Levush), so the two are not interchangeable even in a document.
At a glance
| Hebrew | translit | English | what sets it apart |
|---|---|---|---|
| חדש | chodesh | month; new moon | properly the month's beginning; from chadash, new (Malbim, Rav Hirsch) |
| ירח | yerach | month (whole span) | thirty days as a stretch (Malbim); the ripening month (Rav Hirsch) |
| ירח | yareach | moon | the luminary itself, and the root of yerach |
Where the authorities disagree
The simple view, which the column records and passes over: some say that chodesh is Aramaic and yerach Hebrew. Others, the column says, offer a more sophisticated approach, and it is those that the entry follows.
Malbim: chodesh is the month's beginning, and yerach is a period of thirty days as such, whether or not those thirty days answer to any lunar event. On this reading yerach is a unit of counting, not an astronomical term.
Against that, in truth yerach is related to yareach, the moon, whose lunar movements help fix the month's length. On that basis, the column says, we may posit the cleaner division: chodesh denotes the beginning of the month, yerach the entire month as a whole. The column offers this as a suggestion, not as a ruling.
Rav Hirsch offers another way of dividing them, which the column says fits its own model: chodesh is the month as an abstract unit of time, measured by the moon's light vanishing and returning, while yerach is the month as a vehicle of maturation, the passage of time made tangible in the growth of produce, a month bound to the rules of nature.
Distinctions
chodesh (חדש)
Malbim and Rav Hirsch: the primary sense is not "month" but "the beginning of the month." Hence the places where chodesh stands where one would expect Rosh Chodesh: Bamidbar 28:14, Shmuel I 20:18, Yeshayahu 1:13. The word carries chadash, "new," and chiddush, renewal, so what it names is the novelty of the month. The first of the months is Nissan, whose very meaning is "miracles," because Yetzias Mitzrayim, one of the greatest miracles of all time, happened then.
yerach (ירח) and yareach (ירח)
Rabbi Aharon Marcus ties yerach to oraiach, "path," and to the Aramaic itrachish, "it happened." Marcus does not explain the thematic link between these words; the reading that follows is the columnist's own ("to me it seems fairly clear"). Chodesh, being bound up with "new," alludes to Hashem's introducing new occurrences outside the normal system of nature, which is what we call miracles; that, he suggests, is why chodesh is the word we use colloquially, since we wish to focus on Hashem and His awesome miracles. Yerach, tied to "path," connotes nothing "happening" beyond the regular system of nature: time running its course naturally, as if the month just happened, seemingly without Hashem's miraculous intervention. That, on this reading, is why it is the less common word.
the practical ruling
Rabbi Mordechai Jaffe, the Levush: the custom is that a get dates the month as a yerach and a kesubah as a chodesh. Yerach carries being sent away, from geresh yerachim (Devarim 33:14); chodesh carries newness, and taking a wife is ki yikach ish ishah chadashah (Devarim 24:5).
Rendering guidance
- Trap: English "month" absorbs both. Where the passage turns on the word, render chodesh "new moon" and yerach "month," or gloss the second as "lunar month."
- Bamidbar 28:14, olas chodesh b'chodsho: "the burnt-offering of each new moon in its month" keeps both senses of the same word visible.
- In a get or kesubah discussion, do not normalize the two to one English word; the Levush's whole point is the choice of term.
- Yareach is always "moon," never "month," even where the month is what is being counted.
- Yeshayahu 1:13, chodesh v'shabbos, is "new moon and Shabbos"; the pasuk pairs two days, not a month with a day.
Sources
Rabbi Reuven Chaim Klein, "Old Month versus New Month," What's in a Word?, Ohr Somayach, 1 Nissan 5778 (2018-03-17): raw text in sources/whats-in-a-word/raw/7687-old-month-versus-new-month.md. Primary loci cited: Bamidbar 28:14; Shmuel I 20:18; Yeshayahu 1:13; Devarim 24:5, 33:14; Malbim and Rav Hirsch on chodesh and yerach; Levush on the wording of a get and a kesubah.