Abarim Publications' online Biblical Hebrew Dictionary
The verb ראה (ra'a) primarily means to see or look at or notice (Genesis 6:2, Isaiah 6:5), and, much as in English, came to also mean to understand (Jeremiah 5:12). The imperfect form of this verb (or at least the third person singular) is spelled the same as the verb ירא (yara' II), meaning to regard intently.
The many references to the Lord or an angel 'appearing' uses this same verb, namely in the sense of 'becoming visible' or perhaps rather 'becoming perceivable/understandable' (Exodus 3:2, Genesis 12:7).
Our verb's derivatives are:
- The adjective ראה (ra'eh), meaning seeing (Job 10:15 only).
- The masculine noun ראה (ro'eh), meaning seer (1 Samuel 9:9, Isaiah 30:10).
- The identical masculine noun ראה (ro'eh), meaning prophetic vision (Isaiah 28:7 only).
- The feminine noun ראית (re'ut) or ראות (re'ut), meaning a looking (Ecclesiastes 5:10).
- The masculine noun ראי (re'i), meaning mirror (Job 37:18 only).
- The masculine noun ראי (ro'i), meaning sight or appearance (Genesis 16:13, Job 7:8).
- The feminine noun מראה (mar'a), meaning vision as means of revelation (Genesis 46:2, Numbers 12:6).
- The identical feminine noun מראה (mar'a), meaning mirror (Exodus 38:8 only).
- The masculine noun מראה (mar'eh), meaning sight or appearance (Exodus 3:3, Isaiah 11:3, Ezekiel 8:4).
Note that the latter three nouns are spelled the same as the noun מראה (mur'a), denoting a (fatty?) part of a bird, from the verb מרא (mara' II), meaning to be fat or well-fed.