Merriam-Webster's Collegiate® Dictionary, 11th Edition
DOCTOR
I. noun see: docile
Date: 14th century
1. an eminent theologian declared a sound expounder of doctrine by the Roman Catholic Church, a learned or authoritative teacher, a person who has earned one of the highest academic degrees (as a PhD) conferred by a university, a person awarded an honorary doctorate (as an LLD or Litt D) by a college or university,
2. a person skilled or specializing in healing arts, medicine man ,
3. material added (as to food) to produce a desired effect, a blade (as of metal) for spreading a coating or scraping a surface, a person who restores, repairs, or fine-tunes things, doctoral adjective doctorless adjective doctorship noun
II. verb (doctored; doctoring)
Date: 1712
transitive verb
1. to give medical treatment to, to restore to good condition ; repair ,
2. to adapt or modify for a desired end by alteration or special treatment , to alter deceptively , intransitive verb to practice medicine, to take medicine