metaphor vs. euphemism

[Chungmin Lee]

Dear Dina, ---I would say 'metaphor' is based on meaning similarities,
whereas 'euphemism' is usually based on meaning contiguities. For eaxample,
the 'leg' of a chair comes from the leg of a human or an animal, based on
their similarities in shape and function, whereas 'restrooms' for toilets
come from their use as places for 'rest' is closely related to the general
use of toilets. In that sense, 'euphemism' is mostly part of metonymy.
However, we cannot exclude the possibility of euphemism based on metaphoric
processes, since its function is making something sound better. ---Chungmin
Lee