"obscure boundary" is correct and can be used in written English.
You can use it when referring to a boundary between two things that is not well-defined, unclear, or hard to identify. For example, "The range of emotions humans experience exists in an obscure boundary between pleasure and pain."
1. Obscure boundaries exist during the bidding stage as services are being contracted out . Obscure boundaries exist during the bidding stage as services are being contracted out.
Social service organizations are embedded in community governance institutions and obscure boundaries among community organizations.
During the operation, the lesion was observed to arise from the meninges of the right cerebellopontine angle and have obscure boundaries.
The London government paid without complaint, inaugurating a period of comparative harmony, until Anglo-American war nearly broke out again in 1895 over an obscure Venezuelan boundary dispute.
These points of contact mediate individuals' aspirational desire for upward social mobility as well as their anxiety about the possibility of downward social mobility, and in doing so, they simultaneously highlight and obscure the boundary between classes.
In Ti 58.0 at.% Al ribbon, the Al5Ti3 phase developed as an island in the L10 matrix having an obscure coherent boundary at and below 800°C, while it dissolved during annealing above 800°C.
More specifically, the overlap of tumors and normal tissues may obscure tumor boundaries.
Invasive growth of glioma cells obscures the boundary between normal brain tissue and tumor tissue, making it extremely difficult to accurately diagnose this tumor and delineate the tumor boundary [4].
In particular, subconfluent adherent cells, such as PC12 cells, are often touching each other, and most cells have rough and obscure cell boundaries.
