I am not entirely sure, but I think there IS NO longest such word.You can try different lengths at Wolfram Alpha, with inputs such as:
t_____t
t________t
etc. I tried it with 15 spaces between the two t's, and one of the results is "transcendentalist"; you can try with longer patterns if you like. But please note that just because Wolfram Alpha doesn't have an entry for a specific pattern, that doesn't necessarily mean there is none.
No because a compound is 2 words and t is not a word so t shirt isn't a compound.
snout
B*i*t*c*h*e*s***
If u can use them more often than once the longest wprd i know ia relentlessness
In between the n and the t. didn't
the
quart
thorax
ailment
teamwork
Continue?
turmeric
ballast
Intent.
· suspect
twinkled
* get out * guess what * get it