early 14c., "discomfort, inconvenience, distress, trouble," from Old French desaise "lack, want; discomfort, distress; trouble, misfortune; disease, sickness," from des- "without, away" (see dis-) + aise "ease" (see ease (n.)). Restricted pathological sense of "sickness, illness" in English emerged by late 14c.; the word still sometimes was used in its literal sense early 17c., and was somewhat revived 20c., usually with a hyphen (dis-ease).
mid-14c., disesen, "to make uneasy, trouble; inflict pain," a sense now obsolete; late 14c. as "to have an illness or infection;" late 15c. in the transitive sense of "to infect with a disease, make ill;" from disease (n.). Tyndale (1526) has Thy doughter is deed, disease not the master where KJV has trouble not (Luke viii.49).
form of paralysis, 1877, from French maladie de Parkinson (1876), named for English physician James Parkinson (1755-1824), who described it (1817) under the names shaking palsy and paralysis agitans.
" chronic inflammatory condition of the digestive tract," 1935, for U.S. pathologist Burrill Bernard Crohn, one of the team that wrote the article describing it in 1932.
senium præcox, 1912, the title of article by S.C. Fuller published in "Journal of Nervous and Mental Diseases;" named for German neurologist Alois Alzheimer (1864-1915). The disease name was not common before 1970s; shortened form Alzheimer's is recorded from 1954. The surname is from the place name Alzheim, literally "Old Hamlet."