1. having or showing a disposition to obtrude, as by imposing oneself or one's opinions on others.

2. (of a thing) obtruding itself: an obtrusive error.

3. protruding; projecting.

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 3 words with the pattern -BTR--I--. That is, nine letter words with 2nd letter B and 3rd letter T and 4th letter R and 7th letter I. In alphabetical order, they are:

obtruding

obtrusion

obtrusive

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 4 words with the pattern --T-UD--G. That is, nine letter words with 3rd letter T and 5th letter U and 6th letter D and 9th letter G. In alphabetical order, they are:

detruding

extruding

intruding

obtruding

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 10 words with the pattern --T-U---G. That is, nine letter words with 3rd letter T and 5th letter U and 9th letter G. In alphabetical order, they are:

detouring

detruding

enthusing

extruding

intruding

obtruding

outbuying

outduring

retouring

tittuping

I just got one its: Obligatory

The American Heritage Dictionary has over 3 1/2 pages of words that begin with "ob". You would get a much more comprehensive answer by looking for it, rather than asking for it.