[[An adnominal relative clause is a relative clause that must occur adjacent to the head noun.]]
This roughly corresponds to Croft's (2022) "externally headed" type, but according to Croft, "externally headed relative clauses may be prenominal, postnominal, or extraposed", i.e. he includes extraposed relative clauses, whereas they are treated as distinct from adnominal relative clauses here.
externally headed (STR) = a relative clause construction in which the relative clause head is expressed as an argument of the matrix clause predicate. Example: in I ate the cheesecake [that Carol baked], that Carol baked is an externally headed relative clause; the relative clause head is the cheesecake, which is the Direct Object of the matrix predicate ate. The externally headed strategy is by far the most common strategy for relative clause constructions. Externally headed relative clauses may be prenominal, postnominal, or extraposed. Externally headed relative clauses may use a gap, pronoun-retention, or relative pronoun strategy. (Section 19.2.2)