Motion diagram. A Deaf-recorded clip from the PopSign corpus (CC BY 4.0) exists for this sign and can be placed here.
WHY
“why”
Touch your fingertips to your forehead, then pull the hand away as it closes into a 'Y', brows furrowed.
WH-question: furrowed brows throughout. WHY can also be rhetorical — brows raised — to introduce an answer: 'ME LATE WHY? BUS.'
Where the sign comes from
UnknownNo reliable source. We'd rather say so than invent one.
It starts at the forehead, the locus of thinking and knowing in ASL, and ends in a Y handshape. Teachers often call it 'KNOW plus the letter Y', which would make it an initialized sign — plausible, but we have found no scholarly source confirming that origin.
No sources — which is the point of the “unknown” tier. If you know of a documented account, the historical databases are where to check it.
The sign, taken apart
Every ASL sign is built from a handshape, a place it's made, and a movement. Learn to see these three and you can read and store any sign.
Starts as flat hand, fingers together, thumb along the side; ends as thumb and pinky out, middle fingers closed.
Moves from the forehead to the neutral space.
One-handed.
Palm facing in.