"Lights" in regional, "electrics" with touring or commerical productions has been my experience.
I started with "lights" in education theatre, first time i heard "elex" was a British group on tour, and the audio engineer was named Alex. All kinds of confusing listening to that show being called.
"Elex" may make more sense if you're also calling mic cues, but when you have thirty cues to a page and audio does all mic work on its own (i.e. the audio tech has a script and knows when his mic cues are, I don't have to tell him), "elex" takes way too long to say.
I write an electrics cue as "LX 20" but call "lights 20." LX is so much faster to write or type.... So far that hasn't confused anyone trying to call from my book...and i had someone take over a weekend on my last show with no problems...once they get past the entire book being backwards issue.
More than one syllable gets in the way. The easier to say, the better!:
lights 5 GO
sound 5 GO
sky in GO (or Rail on a Q light)
deck 5 GO
trap open GO
fog GO
pyro (ok, "fire" doesn't really seem appropriate to say over headset) GO
meat GO
pot GO
poop GO (i do a lot of kids shows...)
Along the same lines, i kinda gave up on standbys. It takes a long time to say and ties up my tongue. The beginning of the cue load ("lights...") has the same function, gives em enough time to position finger over button or unlock lineset. Again, haven't had any complaints about it
If there's been more than a page since the last cue, i might say:
"Warn: Swag In on the rail, Sound 30 through 38, Lights 17 through 28."
And that carries through until another pause long enough to turn off the mic and drink some water.
And being dyslexic, i *heart* lettering sound cues. Sadly, this isn't at all practical with computerized sound systems and hundreds of cues *sigh* [1] So i get stuck with sequences like:
Lights 45.6 and Sound 46 GO
Seriously. Why bother saying numbers like that when you're bound to confuse them? Heck, sometimes just "sound and lights GO" works for extended cue sequences.
I find from working backstage that getting a cue like "curtain in" or "house off" is much more clear than "transition 5" or "shift F." People running around pulling ropes don't have time to consult run sheets, so whenever possible i like to give warns that state exactly what they are doing while turning on the appropriate cue light .
[1] The first show i called at this theatre i requested letters and the designer reluctantly agreed. Since we went through the alphabet twice (A, B, C, D, E, F....AA, AB, AC, AD, AE, AF....BA, BB, BC, BC, BE, BF... etc) as the run went on i called one show with NATO alphabet words (modified, things like Bravo, Kilo, Romeo...not something you want to be saying on headset) and themes. A fruit day: Sound apple GO. Soun Banana GO. A music day: Sound alto GO, sound bass GO. Fun while it lasted.