examognomonic 

-adjective
(1) When a phrase, term, or specific word is used on an exam and as used can only represent one key concept. This connection may be vague or not as specific in real life, but is a dead give-away on an exam.

-noun
(1) Often a phrase or word used on standardized testing to avoid the use of another phrase or word. Very commonly seen on exams for medical students. May result in cursing or muttering under the breath if only realized and remembered after the conclusion of the exam.

The use of the phrase "shows retinal pallor with sparing of the macula" rather than stating "cherry-red spot"; where as the later is too easily revealing of the intent of the question. The term "cherry-red spot" is also examognomonic.

examognomonic by Jerome Braun October 3, 2011