1) The sheer span of time between the earliest stages of the Old Testament (c. 1,000 BC) and the modern world makes it difficult to understand the meaning of some terms. We simply do not know all the ranges of meaning of some terms, or the nuances of meaning they could take in different contexts. For example, the meaning of the word selah, often used in Psalms, has been totally lost even in Jewish tradition.
2) The historical and cultural contexts in which languages function are radically different between the biblical world and our own. Some terms, especially metaphorical ones, depend on a certain background of experience to communicate the meaning adequately. For example, the often-used metaphor of water as an object of conquest is nearly incomprehensible without understanding the role of water as a symbol of chaos and disorder in the ancient world (see Baal Worship in the Old Testament).
3) Closely related to this is the understanding that single words often function in a particular literary context that establishes a semantic field in which the term takes on a specialized meaning. Also, some authors may use a common word in a more specialized sense. This simply suggests that in some literary contexts a particular word may have a different range of meaning than in other contexts. For example, the idea of serve is conceptualized differently in priestly sections of the Old Testament than it is in the prophetic literature. And even within the book of Isaiah, the term servant takes on three different ranges of meaning in the three major sections of the book.
4)
Words in most languages tend to have wide ranges of meaning depending on how they are used. While English tends to aim for precision in communication, Hebrew, as an Eastern language, depends far more on context and rhetorical shaping, as well as cultural and historical frames of reference, to carry the meaning of words. Many Hebrew words have much wider possibilities for meaning and carry a built-in ambiguity that may invoke several levels of meaning at once. For example, the term ruach (spirit, breath, wind, movement) is often used with interplay of the various meanings, as in Ezekiels vision of the Valley of Dry Bones (Ezek 37). [emphasis added - Deut. 32.8]
- see
Word Meanings for Old Testament Theology and Study