In context: "...the devices' slings are of alloy-belted plastic and their huge cupped vehicle-receptacles like catcher's mitts from hell, a half dozen or so of the catapults in this like blimp-hangarish things with a selectively slide-backable roof, taking up a good six square blocks of Enfield's brachiform incursion into the Allston Spur..."
Definition: Context isn't too helpful and difficult to find a dictionary with this one.
Best I could find is: Shaped or bent like an arm.
Other:I tried looking up words that might give a suggestion as to meaning. Apparently brach (n.) is any type of female hound that hunts by scent. This later became a term of abuse (cf. bitch)
SNOOT score: 1