The word chumash (Heb. חומש) refers to one of the five books of the Torah, which are collectively known as the Five Books of Moses or the Pentateuch.
The word chumash (pl. chumashim) is derived from the Hebrew word chamesh (חמש), which means “five” or, more accurately, “a fifth.” The chumashim are:
- Bereishit: Genesis.
- Shemot: Exodus.
- Vayikra: Leviticus.
- Bamidbar: Numbers.
- Devarim: Deuteronomy.
The entire set is referred to as the Chamishah Chumshei Torah (חמשה חומשי תורה), literally, the “five fifths of the Torah.” Sometimes they are also collectively called “the chumash.” For example, when the Torah scroll is read in the synagogue, someone may announce that the portion to be read starts on a certain page of the chumash.
The chumash is also one of the staples of every Jewish home and business office. Other staples are: a charity box, a book of Psalms and a prayerbook.
See The Various Components of the Torah and What Is the Torah?.