7-Letter Words Matching O_____A

There are 15 7-letter words that match O_____A. 4 are common words, such as OCARINA and ORGANZA. A rarer one is OVIPARA. In this set, R is the most frequent open letter (7 words). 3 words contain a doubled letter.

Full list 15

ocarinaorganzaoverseaoxymoraolestraoogoniaopuntiaoquassaosmundaosteomaotalgiaouguiyaoothecaostracaovipara

About this list

Words
15 (4 common words)
Common example
ocarina
Rare example
ovipara
Doubled letters
3
Ending in S
0
Most frequent letter
R (7)

Questions

How many 7-letter words matching o_____a are there?

15. 4 of them are common words.

What is a common example?

OCARINA is among the common words in this set.