Marxist
travaux
expense
Maximum.
anthrax
x-raying
Yes, the letter X can be used in the middle of a word in an acrostic poem. The key is for the chosen word to align with the theme or message of the poem and fit with the overall flow of the piece.
PARADOX
Pheonix
boxtops
A seven letter word using the letters would be: virtual.
xrays that's all i coul think of
Some words that have the letter X in the middle are:asexualaxeboxerbuxomcoaxingcoexistDixieepoxiedfixedflexionhexedhoaxinglexismaximmixedmoxienexuspixelpixieproxiessexessixthsixtytaxedTexastoxictoxinvexedvixenwaxen