Any quantum state that doesn't factor is "entangled". That includes both matching, inverse-matching, and more complicated states with more qubits like "last two

Any quantum state that doesn't factor is "entangled". That includes both matching, inverse-matching, and more complicated states with more qubits like "last two qubits contain binary count of how many of the first three qubits are ON". The state |00> + |01> + |10> + |11> factors into (|0> + |1>)(|0> + |1>) so it is not entangled. The state |00> + |11> doesn't, so it is entangled (in this particular basis).