adj

• (geometry) Lacking an angle.
• (cartography, navigation) Having a magnetic deviation of zero.
  "There are two lines on the earth's surface which have been called agonic lines, upon which there is no declination; and where, therefore, the needle is directed along the terrestrial meridian."

adj

• (psychology) Of a mode of social interaction based on threats, displays of power, or inducements of anxiety.
  "[I]n some primates, especially chimpanzees, the hedonic mode of social communication predominates group interactions. […] This is marked by much physical contact, stroking, hugging, lip smacking and sharing. The social interactions are more relaxed, as are the individual members of the group, and there is much focus on physical contact. This is in marked contrast to other more primitive primates, where the agonic mode dominates social behaviour."
• (medicine, obsolete) Occurring shortly before death; agonal.
  "A study of the conditions under which agonic invagination of the intestine occurs will not be out of place in considering the etiology of intussusception. Agonic invagination is very much more common in children than adults, the proportion being, according to [Hermann] Nothnagel, one to fifty. [Luther Emmett] Holt says that agonic invagination is met with in 80 per cent. of the post mortems on infants."