This word turned up the other day in Scarlett Thomas’s The End of Mr Y: “She was playing an organ; an old battered thing from which emanated the most harrowing bombilations.”
The sense intended here is surely the one in the entry in the Oxford English Dictionary: a buzzing or droning. This fits Nathan Bailey’s definition in his Universal Etymological English Dictionary of 1721 that bombilation refers to the humming of bees. This matches its provenance, via an Old French word that derives from Latin bombizatio, a buzzing. Hissing is another possibility, since nineteenth-century writers mention bombilation by angry swans.
However, most of the relatively few appearances of the word I’ve found emphasise loudness as its prime quality, perhaps through mistaken mental associations with bomb.
The sound was the movement, and the movement was the sound. It was too great to be real or sensible. It was holocaust, din, bombilation, charivari, blare, blast. It was hell come there and having its moment.
Waves of Death, a Doc Savage adventure by Kenneth Robeson, 1943. This was a house pseudonym of various authors employed by the US publishers Street and Smith. The author’s real name was Lester Dent.
The verb is known, though also rare, and usually has the sense of creating a loud noise. This is almost certainly its best-known appearance:
“Fire!” cried Mrs. Prothero, and she beat the dinner-gong. And we ran down the garden, with the snowballs in our arms, toward the house; and smoke, indeed, was pouring out of the dining-room, and the gong was bombilating, and Mrs. Prothero was announcing ruin like a town crier in Pompeii. This was better than all the cats in Wales standing on the wall in a row.
A Child’s Christmas in Wales, by Dylan Thomas, based on a piece written for radio in the US and published posthumously in 1955.
The word is so rare these days, however, that nobody is going to dispute your meaning, whether you use it for droning or din.