In the Book of Job, Eliphaz relates one palpable experience he had with a "[**רוּחַ**][1]" (translated *spirit* in the NASB), which had caused the hair of his body to stand on end. 

In [Job 4:14-16][2] we read the following -

>[**Job 4:14-16**][3] (NASB)   
<sup>14</sup> Dread came upon me, and trembling,   
And made all my bones shake.   
<sup>15</sup> Then a spirit passed by my face;   
The **hair** of my flesh bristled up.   
<sup>16</sup> “It stood still, but I could not discern its appearance;   
A form was before my eyes;   
There was silence, then I heard a voice:

The word for hair here is [**שַׂעֲרָה** (H8185)][4] and is **feminine**, which means *a single hair*. That is, this word [appears 7 times in the Hebrew Bible][5], and in two of those instances the word is plural. Why not then the plural form of this word in this verse?

Better, the collective word for hair in Hebrew is [**שֵׂעָר** (H8181)][6] and is **masculine**, and [appears 28 times in the Hebrew Bible][7] although never in the plural form (because the sense of the word is collective). Why then would this more common, collective word for hair not appear instead of the former word (considering that both words are "singular" in form)?

  [1]: http://www.blueletterbible.org/lang/lexicon/Lexicon.cfm?strongs=H7307&cscs=Joe&sstr=1&t=NASB
  [2]: https://www.biblegateway.com/passage/?search=job%204%3A14-16&version=NASB;WLC
  [3]: https://www.biblegateway.com/passage/?search=job%204%3A14-16&version=NASB;WLC
  [4]: http://www.blueletterbible.org/lang/lexicon/Lexicon.cfm?strongs=H8185&cscs=Joe&sstr=1&t=NASB
  [5]: https://i.sstatic.net/hUcOB.png
  [6]: http://www.blueletterbible.org/lang/lexicon/lexicon.cfm?cscs=Joe&sstr=1&strongs=H8181&t=NASB
  [7]: https://i.sstatic.net/MBg0M.png