Definition:
Amicable, derived from latin words which means “friendly” used to suggest cordial relationships.
Alistair Cockburn mentions in his book “Agile Software Development”, for teams success willingness to hear the thoughts of another person with good will and to speak without malice plays a very important role in team building and delivery. The greater the amicability, the more high-quality information can be shared and less information is concealed. Amicability is closely linked to the trust that people have for one another, the sense of community they share. Cockburn also says sometimes amicability can run too high where people can be worried about offending their colleagues that they are afraid to disagree with them or afraid with them are afraid to take the initiative.
Further Reading:
Book: Agile Software Development by Alistair Cockburn
Book: Agile Modeling: Effective Practices for eXtreme Programming and the Unified. by Scott Ambler