15-Letter Words Matching ____OB_________

There are 23 15-letter words that match ____OB_________. 3 are common words, such as IMPROBABILITIES and MICROBIOLOGICAL. A rarer one is RADIOBIOLOGISTS. In this set, I is the most frequent open letter (22 words). 2 words contain a doubled letter.

Full list 23

improbabilitiesmicrobiologicalmicrobiologistssociobiologicalsociobiologistsantiobscenitiesastrobiologistsgnotobioticallyhydrobiologicalhydrobiologistsmicrobarographsneurobiologicalneurobiologistsneuroblastomataopprobriousnesspaleobiologicalpaleobiologistspentobarbitonesphenobarbitonesphotobiologicalphotobiologistsradiobiologicalradiobiologists

About this list

Words
23 (3 common words)
Common example
improbabilities
Rare example
radiobiologists
Doubled letters
2
Ending in S
14
Most frequent letter
I (22)

Questions

How many 15-letter words matching ____ob_________ are there?

23. 3 of them are common words.

What is a common example?

IMPROBABILITIES is among the common words in this set.