Sis forSymmetrical
Something is symmetrical if it exhibits symmetry.
You tickle someone by poking them or running something like your fingers or a feather over their skin. Tickling feels funny and makes you laugh and squirm.
It is almost impossible to tickle yourself. Children tend to be much more ticklish than adults. People are usually ticklish under their feet and on their ribs.
Treacle is any thick liquid made during the sugar refining process. Pale treacle is called golden syrup and very dark treacle is called molasses.
A trickle is a thin stream of water. A trickle is slightly more than a drip but much less than a full stream of water. The waterfall in the picture is only trickling because there hasn't been much rain.
A trickle is often used to describe a small amount of something passing by, as in "he was earning a trickle of money from his second job".
A unicycle is a bicycle with only one wheel. The "uni" at the start of the word means one, just like the "bi" on bicycle means two, and the "tri" on tricycle means three.
Because unicycles only have one wheel they are hard to ride and hard to steer, and they are not seen very often outside of circuses.
Something is vertical if it goes straight up and down. The lines in the picture are vertical. The opposite of vertical is horizontal.