15-Letter Words Matching _________TR____

There are 16 15-letter words that match _________TR____. 2 are common words, such as MICROELECTRONIC and TRIGONOMETRICAL. A rarer one is PHOTOELECTRONIC. In this set, E is the most frequent open letter (15 words). 0 words contain a doubled letter.

Full list 16

microelectronictrigonometricalgalvanometricalinterpenetratedinterpenetratesisoperimetricalphotoelectricalpiezoelectricalamphitheatricalchemoautotrophyenterogastronesinterelectrodesinterelectronicmicroelectrodesphotoautotrophsphotoelectronic

About this list

Words
16 (2 common words)
Common example
microelectronic
Rare example
photoelectronic
Doubled letters
0
Ending in S
5
Most frequent letter
E (15)

Questions

How many 15-letter words matching _________tr____ are there?

16. 2 of them are common words.

What is a common example?

MICROELECTRONIC is among the common words in this set.