day 90 – four types of medium.

• A means by which something is communicated or expressed: here the Welsh language is the medium of instruction.

• The substance in which an organism lives or is cultured.

• A liquid (e.g. oil or water) with which pigments are mixed, with a binder, to make paint.

• The middle quality or state between two extremes; a reasonable balance:the song soon discovers a happy medium between thrash and catchy pop.

Not included:

• An agency or means of doing something:using the latest technology as a medium for job creationtheir primitive valuables acted as a medium of exchange.

• The intervening substance through which sensory impressions are conveyed or physical forces are transmitted: radio communication needs no physical medium between the two stations.

• A particular form of storage material for computer files, such as magnetic tape or discs.

• The material or form used by an artist, composer, or writer:oil paint is the most popular medium for glazing.

• (Plural mediums) A person claiming to be in contact with the spirits of the dead and to communicate between the dead and the living.