"roughly defined" is correct and usable in written English.
You could use it when you are attempting to explain a concept in broad terms, or when you are summarizing something in a concise way. For example: "The concept of success is roughly defined as reaching a goal or outcome one has set for themselves."
Millennials – roughly defined as being born between the early 1980s and early 2000s – make up an important voting bloc.
The gray matter of the cerebral cortex usually is divided into four lobes, roughly defined by major surface folds.
Of course, Midtown South, which is roughly defined as between 34th Street and Chambers Street, is also luring tenants from Midtown.
The mountain pass, roughly defined, is that point on the map where the winding road up is transformed into the winding road down.
Smartphones, roughly defined as cellphones that can store personal information and provide Internet access, were once clunky affairs carried only by the hopelessly geeky or the relentlessly corporate.
Both companies are feverishly trying to mint new headliners capable of drawing the attention of tweens, roughly defined as viewers 9 to 14.
The highlands are roughly defined by the Lužnice River (west), the Dyje River (south), the Morava River (east), and the tributaries of the Elbe (Labe) River (north).
Real estate analysts estimate that while foreigners made up less than 5percentt of total home buyers in Israel last year, they snapped up a third of the luxury properties — roughly defined as those priced above $500 a square foot.
A crush of figures crowd the foreground, orchestrating complex arrangements of limbs, roughly defined in pigment, from which emerges a single tiny white dot that is the light in Marsyas's eye, staring blankly back at us.
In July, the New Jersey Fish and Game Council approved a hunt limited to the area roughly defined by Hunterdon, Morris, Passaic, Sussex and Warren Counties, all in the northwest part of the state.
During the discussion, Fukuyama tries to explain how "realistic Wilsonianism," the foreign policy he proposes in his latest book, differs from plain old liberal internationalism, roughly defined as President Clinton's foreign policy.
