According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 27 words with the pattern SUBT-----. That is, nine letter words with 1st letter S and 2nd letter U and 3rd letter B and 4th letter T. In alphabetical order, they are:
subtaxons
subtenant
subtended
subtenses
subtenure
subthemes
subtilely
subtilest
subtilins
subtilise
subtility
subtilize
subtitled
subtitles
subtonics
subtopian
subtopias
subtopics
subtorrid
subtotals
subtracts
subtrends
subtribes
subtropic
subtruded
subtrudes
subtunics