15-Letter Words Matching ____O_______N__

There are 28 15-letter words that match ____O_______N__. 9 are common words, such as ACKNOWLEDGMENTS and DISCONTENTMENTS. A rarer one is VIDEOCONFERENCE. In this set, I is the most frequent open letter (26 words). 1 words contain a doubled letter.

Full list 28

Common words

acknowledgmentsdiscontentmentsdiscouragementsimprovisationalmicroelectronicnitroglycerinesphotoengravingsphotofinishingsradiotelephonesazidothymidinesdisconcertmentshydrocortisones
acknowledgmentsdiscontentmentsdiscouragementsimprovisationalmicroelectronicnitroglycerinesphotoengravingsphotofinishingsradiotelephonesazidothymidinesdisconcertmentshydrocortisonesmalnourishmentsnoncommissionednonconventionalradiotelephonicbenzodiazepinescyproheptadineshydroxyprolinesintrospectionalmethoxyfluranespentobarbitonesphenobarbitonesphotoelectronicphytopathogenicphytoplanktonicthyrocalcitoninvideoconference

About this list

Words
28 (9 common words)
Common example
acknowledgments
Rare example
videoconference
Doubled letters
1
Ending in S
17
Most frequent letter
I (26)

Questions

How many 15-letter words matching ____o_______n__ are there?

28. 9 of them are common words.

What is a common example?

ACKNOWLEDGMENTS is among the common words in this set.