The phrase "a relatively formal" is correct and usable in written English.
It can be used to describe something that is somewhat formal in nature, often in comparison to something else that may be less formal.
Example: "The meeting will be held in a relatively formal setting, so please dress appropriately."
Alternatives: "somewhat formal" or "fairly formal".
My parents lived a relatively formal life.
The father and son have always had what Adam describes as a "relatively formal relationship", so working together definitely led to some "uncomfortable moments".
"Our entire conversation has been conducted in a relatively formal standard English despite the fact that I know a lot of words that will make people's hair crawl.
Victory Gardens has long had its own stable of playwrights, but Mr. Zacek shaped the group into a relatively formal writing ensemble only in 1996.
"You didn't have to restrict yourself to the bluegrass palette, which is a relatively formal one," Mr. Asher recalled in a telephone interview.
Denmark started out the implementation process with high ambitions and a relatively formal approach, whereas the Netherlands from the outset chose to follow a more pragmatic course.
The funders with a central 'pot' for OA organise it on a scale which ranges from relatively formal to completely ad hoc.
Opera recitals are usually relatively formal affairs, so it was a treat to hear Mr. Calleja, 33, a tenor from Malta, in such an intimate space.
In relatively formal terms, the image diagrams an explosion of visual energy that was subsumed, but never lost, as Evans's emotional content deepened.
After Yvette's rapid decline and sudden death, Nathalie, who has inherited her mother's cat, Pandora, must make the funeral arrangements, and, strangely, her relatively formal discussion with the priest delivers a crucial vision of the world according to Nathalie, and according to Hansen-Løve as well.
The atmosphere was sober and relatively formal, for every ten tourists in a puffer jacket among the crowds there seemed to be a veteran of one war or another, some visibly distinguished by a uniform, others by simply wearing his or her medals pinned to a coat or jacket.
