After healing ten lepers, one, whom Luke identifies as a Samaritan, returns:

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> Then one of them, when he saw that he was healed, turned back, praising God with a loud voice; and he fell on his face at Jesus' feet, giving him thanks. Now he was a Samaritan.  
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> (Luke 17:15-16) [ESV]
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Jesus calls the Samaritan man a ἀλλογενής, a foreigner:

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> Was no one found to return and give praise to God except this foreigner?” (Luke 17:18)
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> οὐχ εὑρέθησαν ὑποστρέψαντες δοῦναι δόξαν τῷ θεῷ εἰ μὴ ὁ ἀλλογενὴς οὗτος
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About [ἀλλογενής](https://www.blueletterbible.org/lang/lexicon/lexicon.cfm?Strongs=G241&t=KJV) Thayer's has:

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> ἀλλογενής, -ες (ἄλλος and γένος), sprung from another race, a foreigner, alien: Luke 17:18. (In the Sept. [Genesis 17:27; Exodus 12:43, etc.], but nowhere in secular writings.)
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While Luke has the only use of the word in the New Testament, it is [used 29 times](http://www.obohu.cz/bible/index.php?hledat=g241&k=2K&styl=LXXK&kap=1&kde=1) in the LXX, but according to the Thayer's entry, nowhere in secular writings.

1. How is a Samaritan a foreigner and is the use in Luke consistent with the use in the LXX?
2. If ἀλλογενής is nowhere used in secular writings, was this word "created" by the LXX translators as a way to distinguish a certain type of foreigner, such as a Samaritan?