Synonyms for Borderline:

adj.

all (adjective)
marginal.
inexact (adjective)
equivocal, problematic, dubitable, marginal, doubtful, indeterminate, ambiguous, uncertain, unclear, indecisive.
problematical (adjective)
at issue.

n.

close, practically, barely, nearly, almost, near, all but, scarcely, well-nigh, hardly. difference, divergence, variation, rim, distinction, collision, brink, variety, diversity, contrast, periphery, verge, edging, contradiction, a world of difference, fringe, brim. threshold, candidate, cheat sheet, crib, examiner, crib note, point, certificate, examination, mock, exam. doubtful, questionable, in question, uncertain, in doubt, indeterminate, indecisive, problematical, certain, clouded, clear, iffy, at issue, dubitable, chancy, ambiguous, problematic, equivocal, dubious, unclear, inconclusive, unsure. borderline (noun)
delimitation, border, boundary line, minimal, minimum, marginal.
marginal (noun)
indeterminate, doubtful, problematic, questionable, uncertain.

Other synonyms:

dubitable, examiner, edging, crib note, fringe, chancy, cheat sheet, clouded. exam, problematical, verge, mock, unclear, indeterminate, brink, unsure, rim, inconclusive, certificate, iffy. brim, uncertain, indecisive, problematic, threshold, periphery, ambiguous. dubious, candidate, doubtful, examination, questionable, equivocal. crib. point. Other relevant words:
distinction, chancy, diversity, dubious, periphery, examiner, variety, inconclusive, at issue, questionable, examination, rim, exam, divergence, fringe, verge, doubtful, almost, brim, iffy, hardly, practically, ambiguous, close, well-nigh, in doubt, candidate, collision, in question, equivocal, clouded, problematic, uncertain, contradiction, point, unsure, crib, certificate, mock, variation, difference, dubitable, indecisive, problematical, unclear, edging, barely, nearly, indeterminate, scarcely, clear, brink, contrast, threshold, near.

Usage examples for borderline

  1. " That woman has been dangerously close to the borderline of sanity for as long as she's been here. – Dearest by Henry Beam Piper
  2. This was a large photographic bird's- eye map of a country which looked very much like Arizona, or the wild places anywhere next the Mexican borderline – The Thunder Bird by B. M. Bower