Merriam-Webster Collegiate Dictionary - discern

 verb  Etymology: Middle English, from Middle French ~er, from Latin ~ere to separate, distinguish between, from dis- apart + cernere to sift — more at dis-, certain  Date: 14th century  transitive verb  1.  a. to detect with the eyes ~ed a figure approaching through the fog  b. to detect with senses other than vision ~ed a strange odor  2. to recognize or identify as separate and distinct ; discriminate ~ right from wrong  3. to come to know or recognize mentally unable to ~ his motives  intransitive verb to see or understand the difference  • ~er noun  • ~ible also ~able adjective  • ~ibly adverb