In mathematics, x is commonly used as the name for an independent variable or unknown value. The modern tradition of using x to represent an unknown was introduced by René Descartes in La Géométrie (1637).[5] As a result of its use in algebra, X is often used to represent unknowns in other circumstances (e.g. X-rays, Generation X, The X-Files, and The Man from Planet X; see also Malcolm X).
XCOM的正確讀法是“X-COM”。
X的含義是“未知”，而COM是指揮部的縮寫。
關於X的含義，維基上給瞭如此說法。
In mathematics, x is commonly used as the name for an independent variable or unknown value. The modern tradition of using x to represent an unknown was introduced by René Descartes in La Géométrie (1637).[5] As a result of its use in algebra, X is often used to represent unknowns in other circumstances (e.g. X-rays, Generation X, The X-Files, and The Man from Planet X; see also Malcolm X).
在數學中，x通常用作獨立變數或未知值的名稱。 RenéDescartes在LaGéométrie（1637）中介紹了使用x代表未知的現代傳統。作為其代數使用的結果，X在其他情況下也用來表示未知（例如，X射線，X世代，X檔案和X星來客，也參見Malcolm X）。
因此X也有“未知”（敵人）的意思，在1代中也有“Enemy Unknown”的副標題。
至於COM的縮寫，應該是效仿“Special Operations Command”縮寫為“SOCOM”，所以用COM來指代“Command”。從遊戲中玩家要扮演“Commander”來說，這應該是最合理的可能。