* Phonetically: The word "rail" is a single syllable with a short vowel sound (the "ai" makes an "ay" sound). So, in terms of pronunciation, it is a short sound.
* Contextually: The word "rail" can be used in a number of ways, some of which might be associated with longer sounds. For example:
* "The train ran along the rail" - The "rail" here might evoke the long, continuous sound of the train moving.
* "The rail fence was old" - The "rail" here might evoke the sound of wood creaking, which could be longer.
Ultimately, the "shortness" of the sound of "rail" depends on the context in which it is used.