There are several possibilities for the original Semitic pictograph including (a fish), (possibly a thorn), (a window?) and (a thorn). The pictograph is used almost exclusively through the history of this letter. This picture has the meanings of pierce and sharp. This letter also has the meaning of a shield as thorn bushes were used by the shepherd to build a wall or shield, made to enclose his flock during the night to protect them from predators. Another meaning is to grab hold as a thorn is a seed that clings to hair and clothing.

Of all the letters this is the most difficult to reconstruct due to the limited archeological and textual support. The Modern Hebrew name for this letter is samech, which is a word that means support, with no apparent connection to a two letter parent root or to the meaning of the original picture of this letter. The Arabic alphabet does not have this letter and the Greek letter derived from this letter is called the ksi. The 21st letter of the Hebrew alphabet (ש) has two names and sounds, Shin (sh) and Sin (s). All the words using the sin are related in meaning to the words using a samech in the same place as the sin. It is possible that the original name for the samech was sin, meaning thorn, and later was divided into the samech and sin (which then became associated with the shin).

The original sound for this letter must be an "s" to which the samech and sin both agree. The Greek sound for the letter is "ks", similar to the "s".

The early Semitic evolved into the in the middle Semitic. This letter continued to evolve into in the late Semitic. This letter became the ס in the modern Hebrew alphabet. The late Semitic is reversed in the Greek alphabet becoming the x and X. The Greek letter X became the Latin X.