(like) water off a duck's back

: the liquid that descends from the clouds as rain, forms streams, lakes, and seas, and is a major constituent of all living matter and that when pure is an odorless, tasteless, very slightly compressible liquid oxide of hydrogen H₂O which appears bluish in thick layers, freezes at 0° C and boils at 100° C, has a maximum density at 4° C and a high specific heat, is feebly ionized to hydrogen and hydroxyl ions, and is a poor conductor of electricity and a good solvent

: a natural mineral water

: a particular quantity or body of water: such as

: to moisten, sprinkle, or soak with water

: to supply with water for drink

: to supply water to

: from a place or position

: at a distance in space or time

: from a course : aside

used as a function word to indicate physical separation or distance from a position of rest, attachment, or union

: to seaward of

: from the possession or charge of

: seaward

: right

: more removed or distant

: to go away : depart

: kill, murder

: competition : contest

: any of various swimming birds (family Anatidae, the duck family) in which the neck and legs are short, the feet typically webbed, the bill often broad and flat, and the sexes usually different from each other in plumage

: the flesh of any of these birds used as food

: a female duck — compare drake

: to thrust under water

: to lower (the head, the body, etc.) quickly : bow

: avoid, evade

: an instance of ducking

: a durable closely woven usually cotton fabric

: light clothes and especially trousers made of duck

: the rear part of the human body especially from the neck to the end of the spine

: the body considered as the wearer of clothes

: capacity for labor, effort, or endurance

: to, toward, or at the rear

: in or into the past : backward in time

: to or at an angle off the vertical

: being at or in the back

: distant from a central or main area

: articulated at or toward the back of the oral passage : formed deep within the mouth

: to support by material or moral assistance

: substantiate

: to assume financial responsibility for