13-Letter Words Matching __R________U_

There are 18 13-letter words that match __R________U_. 8 are common words, such as CARBONIFEROUS and CARTILAGINOUS. A rarer one is PORCELLANEOUS. In this set, O is the most frequent open letter (17 words). 5 words contain a doubled letter.

Full list 18

carboniferouscartilaginouschrysanthemumperspicaciousserendipitousstreptococcussurreptitioustyrannosaurusboraginaceouscarcinomatousferrochromiumforeconsciousperichondriumstratocumulusstrobilaceousgarnetiferousparamyxovirusporcellaneous

About this list

Words
18 (8 common words)
Common example
carboniferous
Rare example
porcellaneous
Doubled letters
5
Ending in S
15
Most frequent letter
O (17)

Questions

How many 13-letter words matching __r________u_ are there?

18. 8 of them are common words.

What is a common example?

CARBONIFEROUS is among the common words in this set.