decent; dignity; dainty; doctor;

decent (adj.)

1530s, "proper to one's station or rank," also "tasteful,"
from Middle French décent, or directly from Latin decentem (nominative decens) "becoming, seemly, fitting, proper," present participle of decere "to be fitting or suitable,"

from PIE *deke-, from root *dek- "to take, accept, to receive, greet, be suitable"
(cf. Greek dokein "to appear, seem, think," dekhesthai "to accept;"
Sanskrit daśasyati "shows honor, is gracious," dacati "makes offerings, bestows;"
Latin docere "to teach," decus "grace, ornament").

Meaning "kind, pleasant" is from 1902. Are you decent? (1949) was originally backstage theater jargon for "are you dressed."

dignity (n.)

early 13c., from Old French dignite "dignity, privilege, honor,"
from Latin dignitatem (nominative dignitas) "worthiness,"
from dignus "worth (n.), worthy, proper, fitting"
from PIE *dek-no-, from root *dek- "to take, accept"

dainty (n.)

c.1300, "excellence, elegance; a luxury,"
from Old French deintie (12c.) "price, value," also "delicacy, pleasure,"
from Latin dignitatem (nominative dignitas) "greatness, rank, worthiness, worth, beauty," from dignus "worthy"

doctrine (n.)

late 14c., from Old French doctrine (12c.) "teaching, doctrine,"
and directly from Latin doctrina "teaching, body of teachings, learning,"
from doctor "teacher" .

doctor (n.)

c.1300, "Church father,"
from Old French doctour,
from Medieval Latin doctor "religious teacher, adviser, scholar,"
in classical Latin "teacher," agent noun from docere "to show, teach, cause to know,"

originally "make to appear right," causative of decere "be seemly, fitting" (see decent).

Meaning "holder of highest degree in university" is first found late 14c.; as is that of "medical professional" (replacing native leech (n.2)), though this was not common till late 16c. The transitional stage is exemplified in Chaucer's Doctor of phesike (Latin physica came to be used extensively in Medieval Latin for medicina).

Similar usage of the equivalent of doctor is colloquial in most European languages:
cf. Italian dottore, French docteur, German doktor, Lithuanian daktaras,
though these are typically not the main word in those languages for a medical healer.

For similar evolution,
cf. Sanskrit vaidya- "medical doctor," literally "one versed in science."
German Arzt,
Dutch arts
are from Late Latin archiater,
from Greek arkhiatros "chief healer,"
hence "court physician."
French médecin is a back-formation from médicine, replacing Old French miege, from Latin medicus.

-iatric

word-forming element from Greek iatrikos "healing,"
from iatros "physician, healer" (related to iatreun "treat medically," and iasthai "heal, treat");
of uncertain origin, perhaps from iaomai "to cure," related to iaino "heat, warm, cheer,"
probably from a root meaning "enliven, animate."