Semi = Large tractor-trailer rig

[Rudolph C Troike]

Howdy,all--

        Here in the Southwest, where we are overrun with these things, I
hear them referred to only as /sImayz/ or /sEmayz/ (primary stress on
first syllable, secondary [word-level] or tertiary stress on the second).
Like Natalie, my Texan ears don't readily distinguish /Im/ from /Em/, so I
can't swear as to the quality of the first vowel. /sImiy/ is used only as
the first part of a compound, as in "semi-tractor trailer rig".

        Rudy Troike