Some commonly-used words in English which end in 'mt' are dreamt, undreamt, and possibly daydreamt. Other derivatives are outdreamt and redreamt.
An uncommon word in this category is 'screamt' (a Shakespearean alternative to 'screamed') .
This list doesn't include scientific terms or abbreviations such as 'mt' (mountain), 'pmt' (PreMenstrual Tension), 'mgmt' (management), names, non-English words and so on.
An amt is also the term for an administrative district in Denmark and Norway. (Ref Webster's English language dictionary, 1913)
Rarely used words found in some dictionaries are:
a 6 letter word ending with a w is borrow.
Genius is a 6 letter word ending in ius
jigsaw The 6 letter word ending with w is hollow, sorrow, pillow, etc.
afloatbobcatcombatdefeatformatnonfatreheatrepeatthreatthroatunseat
BehoofHereofReroofUnroof.
A 6 letter word for an offensive remark ending with t is cumquat.
TRAGIC
league
Father
German
minute
Gyrate