Why is the prefix "Trans" shortened to "X"? [duplicate]

In technical literature as well as aircraft user interfaces where there is not enough space to write the whole word, the prefix "trans" is shortened to "x".

Transmit -> Xmit
Transfer -> Xfer

I am interested to know what is the origin of this. I am curious because "Ex" and "Trans" do not have a similar sound.

Solution 1:

X is commonly used to refer to cross because of its shape of two lines crossing.

Trans- means cross/across. Trans- and cross- are interchangeable in many cases.

From Wikipedia (emphasis mine):

In abbreviations, it can represent trans- (e.g. XMIT for 'transmit', XFER for 'transfer'), cross- (e.g. X-ing for 'crossing', XREF for 'cross-reference'), Christ- as shorthand for the labarum (e.g. Xmas for 'Christmas', Xian for 'Christian'), the crys- in 'crystal' (XTAL), or various words starting with ex- (e.g. XL for 'extra large', XOR for 'exclusive-or').

Example: a transatlantic flight is one that crosses the Atlantic, and something that is transdermal crosses through the skin.

The trans- in transmit and transfer is analogous to transatlantic.

Crossing a mit or a fer makes perfect sense.

• -Mit is from the Latin mittere which means to send.
• -Fer is from the Latin ferre which means to bear or carry.

'Transmit' often means to send across something or over a specific medium and 'transfer' can be to carry across from one to another.

Therefore trans- is often replaced with X- in certain words.

Solution 2:

In addition to the other edifying answers and comments: from an information-theory viewpoint, given the rarity of initial "x" in English words, the presence of it (especially if unpronounceable) is a clear signal that there is something at play slightly out of the ordinary, and it will not be easily mistaken for anything else. That is, information-theory-wise, the chance of misunderstanding is low (more technically/precisely, the error-correction properties of this usage are excellent).

Solution 3:

Oddly enough, 'Tx' is used to describe 'a transmitter' or 'to transmit something' and is very much relevant in electronics domain. Similarly, 'Rx' describes 'a receiver' or 'to receive something/reception of signal'. Here is a picture which shows Tx and Rx use in electronics:

Picture source

Solution 4:

OED:

trans-, prefix

Etymology: The Latin preposition trans, across, to or on the farther side of, beyond, over’, also used in combination, (1) with verbs, (2) adjectives (3) the neames of geographical features and names, etc.

e.g. transcribe, transcript, transcription, tranship, transport, transmarine, transmural, transatlantic,

The shape of the letter X is described as a cross: The letter is formed by one line crossing another:

b. The letter considered with regard to its shape: chiefly attributive and in other combinations. Hence identified with a cross. X's and O's: the game of noughts and crosses. X chair, a chair in which the underframe resembles the letter X in shape; so X-frame (usually attributive).

1976 Country Life 27 May (Suppl.) 486/1 Late 18th century wheel-back armchairs with saddle seats and X-frame legs.

d. [the letter or mark 'X'] Used to mark a location on a map or the like; esp. in X marks the spot and variants.

1918 J. M. Barrie Echoes of War 5 In the rough sketch drawn for to-morrow's press, ‘Street in which the criminal resided’..you will find Mrs. Dowey's home therein marked with a X.