Seah is a standard dry measure in ancient Israel, equal to approximately one-third of an ephah (about 7 liters or 7.5 quarts). It was used to measure grain, flour, and other dry goods. The word appears in Genesis 18:6 when Abraham instructs Sarah to take 'three seahs' of fine flour to make bread for the divine visitors. In 2 Kings 7:1, the prophet Elisha promises that 'a seah of fine flour' will sell for a shekel — a sign of miraculous provision after siege.
The seah appears in contexts of divine hospitality and miraculous provision. Abraham's three seahs for the Lord at Mamre represent the lavishness of true hospitality before God. The Isaiah 27:8 use of seah (in 'measure by measure/in moderation') shows God's disciplined, careful dealing with His people. The most theologically memorable use may be implicit: Luke 13:21 records Jesus' parable of the woman who hid leaven in three measures (sata = Greek equivalent of seah) — the kingdom expanding from within, hidden but pervasive.