Question

define latent heat of fusion and boling point of a liquid

Answer 1

latent heat of fusion means its the state in which liquid can change it property from liquid state to gaseous state. Boiling point of liquid means it's a state when liquid starts boiling in certain temperature and it changes its state from liquid to gas

Answer 2

the amount of heat required to convert 1 kg of solid into liquid at atmospheric pressure (without any change in its temperature) is called latent heat of fusion.
the temperature at which a liquid starts boiling at the atmospheric pressure is known as it's boiling point.
hope it helps:-)