If someone is motherly, they are loving and kind in the way we expect a good mother to be: they notice when you are tired, they feed you, they worry, they speak softly when you are hurt. You can call a woman motherly, but also a look, a voice, a piece of advice, a hug. The person does not have to be anyone’s mother — a teacher or an aunt can be motherly, and in a story even a man might give a motherly smile, though that last use is less common and some people will raise an eyebrow. Motherly is warmer than maternal. Maternal is the more school-and-hospital word (maternal grandfather, maternal instinct); motherly is about manner and feeling. The same form also works as an adverb (she smiled motherly), though “in a motherly way” is clearer. Slightly literary; “kind” is what people say every day. Though actually, like motherliness, it names an ideal of care, not a rule that every mother is gentle.