In what sense is Jesus understood to be "the only begotten son of God" in LDS teaching? In a comment made on a previous question I asked, someone directed me to Moses 1:35 in the Pearl of Great Price.  I read the context and saw Moses 1:32–33, which interested me as well.  The text is as follows:

And by the word of my power, have I created them, which is mine Only Begotten Son, who is full of grace and truth.
And worlds without number have I created; and I also created them for mine own purpose; and by the Son I created them, which is mine Only Begotten.

In LDS teaching, Lucifer and Jesus are spiritual brothers, and, indeed, we are all brothers of both Jesus and Lucifer—both of whom are our elder brothers.
So, in what sense, then, is Jesus the Only Begotten Son of God according to LDS teaching, when in the pre-mortal life Elohim did have multiple sons (and daughters)?
I had to go do a little looking around to see how the phrase "Only Begotten Son" as it appears in the Bible is interpreted in other denominations. It appears that there is some disagreement.

Within LDS theology, here is how the term is used in the Book of Mormon and also in the Doctrine and Covenants. Usage of the term "Only Begotten Son" is pretty consistent across all these references.

Simply enough, Latter-day Saints understand "Only Begotten Son" to mean that Christ is the only literal, physical Son of God. He is divine and set apart in that very symbolic and important way.

The LDS Bible Dictionary makes an interesting point about the use of the term "Son of God" that makes reference to being The Only Begotten (emphasis my own):


  It does not appear from the Gospels that our Lord frequently applied this title to Himself (but see Matt. 27:43; Luke 22:70; John 5:25; 9:35–37; 10:36; 11:4), though we often find it used by others in speaking to Him (Matt. 14:33; 16:16; Luke 4:41; John 1:49; 11:27); and of Him (Mark 1:1; John 3:18; 20:31). But there is ample proof that He claimed to be the Son of God in a sense that was true of Him and of no one else (see Matt. 11:27 [Luke 10:22]; Mark 13:32). He speaks of Himself as Son of God, and of others as sons of God, but there is not a single passage in which the sonship of others is spoken of as being the same thing as His own. So too He speaks of “my Father” and “your Father,” but never of “our Father.” (The Lord’s Prayer is no exception, as it was intended for the disciples’ use.) There is a consistency in scripture, ancient and modern, that Jesus Christ is literally the Son of God the Father, being the Only Begotten of the Father in the flesh. See Jacob 4:5; D&amp;C 20:21; Moses 6:52, 54, 57.