It is true that most often the Hebrew word yom (“day”) means “twenty-four hours.” However, this is not definitive for its meaning in Genesis 1 for several reasons. First, the meaning of a term is not determined by majority vote, but by the context in which it is used. It is not important how many times it is used elsewhere, but how it is used here. Second, even in the creation story in Genesis 1–2, “day” (yom) is used of more than a twenty-four-hour period. Speaking of the whole six “days” of creation, Genesis 2:4 refers to it as “the day” (yom) when all things were created. Third, and finally, yom is elsewhere used of long periods of time, as in Psalm 90:4, which is cited in 2 Peter 3:8: “A day is like a thousand years.” (Norman L. Geisler, 639)
According to Geisler, the time of a “day”