13-Letter Words Matching T________O___

There are 19 13-letter words that match T________O___. 7 are common words, such as TESTOSTERONES and THOROUGHGOING. A rarer one is TRANSPERSONAL. 3 words contain a doubled letter.

Full list 19

testosteronesthoroughgoingthundercloudsthundershowerthunderstormstransnationaltroubleshootsthoroughwortstoxoplasmosistransactionaltranslationalteleutosporesterminationaltetrapyrrolesthrottleholdsthunderstonestoxoplasmosestransfusionaltranspersonal

About this list

Words
19 (7 common words)
Common example
testosterones
Rare example
transpersonal
Doubled letters
3
Ending in S
11

Questions

How many 13-letter words matching t________o___ are there?

19. 7 of them are common words.

What is a common example?

TESTOSTERONES is among the common words in this set.