a spoken word: an utterance, saying, or promise, most often God's.
This is a poetic word for something that has been said. It belongs almost entirely to Hebrew poetry, above all the Psalms, where it is a favorite term for God's spoken word. It overlaps heavily with the ordinary Hebrew word for "word," but it keeps a more elevated, deliberate ring, the kind of word you reach for in a psalm rather than in a report.
Who is speaking is what shades its meaning. When a person is the speaker, it simply means their speech, the words coming out of their mouth. Far more often the speaker is God, and then it can lean toward one of several familiar notes: a promise the faithful cling to, a teaching they treasure and obey, a word so pure and tested that it can be relied on completely, or a decree that carries out exactly what it announces.
The great showcase is Psalm 119, where this word appears again and again as one of several near-synonyms for God's revealed word. There it slides easily between God's promise and God's instruction, because to the psalmist they are two sides of one thing: the word by which God has bound himself and by which he directs a life.