Noun

• S: (n) intermediate (a substance formed during a chemical process before the desired product is obtained)

Verb

• S: (v) intercede, mediate, intermediate, liaise, arbitrate (act between parties with a view to reconciling differences)

Adjective

• S: (adj) intermediate (lying between two extremes in time or space or state)
• S: (adj) average, intermediate, medium (around the middle of a scale of evaluation)