Mourning can already be a verb, because it is an action.
For example "she is mourning the death of her goldfish".
Other verbs are mourn, mourns and mourned.
Moaned, the past-tense of moan, as in the action "to moan" is a verb. Moaned as in the description "a mournful cry" is a noun.
The people were mournful for their president's death
The noun form of the adjective mournful is mournfulness.
Mournful Unconcern was created in 1983.
Mournful Congregation was created in 1993.
The duration of Mournful Unconcern is 1.83 hours.
the wife was mournful at her husbands death
When my friend went back to Taiwan, I felt mournful.
mournful- a act thet damages or hurts
Mournful Cries was created on 1988-08-22.
It was a mournful day in the United States when President Kennedy was shot.
This sentence is in the natural order: the subject (the siren) is first, and it is followed by the verb (wailed).