IUPAC uses the prefix "isocyano" for the systematic nomenclature of isocyanides: isocyanomethane, isocyanoethane, isocyanopropane, etc.
The sometimes used old term "carbylamine" conflicts with systematic nomenclature. An amine always has three single bonds, whereas an isocyanide has only one single and one multiple bond.
The isocyanamide functional group consists of a amino group attached to an isocyano moiety.
for nomenclature as suffix of isonitrile or prefix of isocyano is used depending upon priority table.