Boyish describes qualities, behaviors, or appearances that remind people of boys, usually in a positive or endearing way. A boyish grin is eager and mischievous, the kind that suggests someone is up to something fun. Boyish enthusiasm means approaching things with the fresh excitement and energy that young boys often bring to new adventures.

When describing appearance, boyish usually means youthful features: a slim build, short hair, or a face without the angles that develop later. An adult woman with short hair and athletic features might have a boyish look. A teenager who hasn't fully grown yet might have boyish features.

The word can describe anyone, regardless of gender. A boyish sense of humor might involve pranks and silly jokes. Boyish charm combines playfulness with innocence. When someone describes a grandfather as having a boyish twinkle in his eye, they mean he's kept that sense of wonder and fun even as he's aged.

Note that boyish typically suggests positive qualities: energy, enthusiasm, playfulness, and charm. It's related to childish, but where childish often means immature in a negative way, boyish usually celebrates the better parts of being young.