X voiceless velar fricative
X is voiceless, which means it is produced without vibrations of the vocal cords.
I would say in other words X = silence
just like finger over lips - shhhh means silence
Phoenician Samek gave rise to the Greek Xi
Samekh is also a voiceless alveolar fricative as is our letter X
Samekh and Mem form the abbreviation for the Angel of Death, whose name in Hebrew is Samael.
Mem is believed to derive from the Egyptian hieroglyphic symbol for water