The very common verb אמר ('amar) occurs all over the Semitic language spectrum and basically means to utter, say or tell (Genesis 3:1, Numbers 22:28, Psalm 40:10), command (Numbers 15:38, Joshua 11:9), promise (1 Chronicles 27:23, Esther 4:7) and even to think (in the construction אמר בלבב ('mr blbb); "to say in one's heart" - Genesis 8:21, Deuteronomy 8:17, see our article on לבב, lebab, meaning heart).
This verb amar should be distinguished from the verb דבר (dabar) in that dabar generally reflects an entire message, while 'amar tends to reflect the act of speaking. When, for instance, the name of the Lord occurs in conjunction with the word 'amar, it's translated as something like "the Lord spoke," or "the Lord promised," while the word dabar would usually lead to "the Word of the Lord . . . " See the name Dabar Yahweh.
The masculine noun אמר ('omer), meaning speech or word (Job 6:26, Proverbs 2:1) or even promise (Psalm 77:9), decree (Job 20:29) or plan (Job 22:28).
The feminine noun אמרה ('imra), meaning utterance or speech (Deuteronomy 32:2, Psalm 119:103, Isaiah 5:24).
The similar but slightly differently pronounced feminine noun אמרה ('emra), also meaning utterance or speech (Lamentations 2:17 only).
The masculine noun מאמר (ma'amar), meaning word or command (Esther 1:15, 2:20 and 9:32 only).
Most notable is the masculine derivation אמיר ('amir), which occurs twice in the Bible — in Genesis 49:21 and in Isaiah 17:6 — where it means top or summit of a tree. It's unclear how this beautiful metaphor is formed. It may be that the Hebrews saw the fruits of a tree as its words, but it may also be that a man's words were regarded as his fruits. But it certainly sheds clarifying light on the Biblical scenes where birds pick fruits from trees, or when men somehow are hanging from or sitting on a tree's branches (Absalom, 2 Samuel 18:9; Zaccheus, Luke 19:1-10).