1. to float; to set afloat; to launch
子供が紙の船を川に浮かべた。The child floated a paper boat on the river.
2. to show on one's face (smile, sadness, etc.)
笑顔を浮かべてそんなことを言う。They say such things with a smile on their face.
3. to recall; to call to mind; to imagine; to think of