materinski

1. maternal; motherly
   Materinska ljubav nema granica. — A mother's love knows no bounds.

2. maternally; like a mother
   Starija sestra se materinski brinula o mlađoj braći. — The older sister looked after her younger brothers like a mother.

For 'native language', maternji jezik is more usual in Serbia; materinski jezik is also used in Serbian and is characteristic of the Croatian standard. In other collocations (materinska ljubav, materinski instinkt) materinski and majčinski are interchangeable.