A symbol that represents a deaf and blind person could be a combination of the sign language symbol for "deaf" and Braille characters for "blind," perhaps overlapping or intertwined to visually convey both conditions.
As a symbol, a screw would represent technological sophistication.
You think probable to the chemical symbol of an element.
A backbone?
poridge poridge
What symbol would represent a chlorine ion that has ionized to have a stable electron configuration?
Good Samaritan.
Rectangles
A symbol to represent happiness would be bluebirds (happy birds...),flowers,a beautiful scene, smiley face, rainbow...........Anything that makes you happy.....
I presume you mean 'a blind person'. Impossible to describe colours to a person who had been blind from birth.
Any symbol that represents you and your sister would represent sisterhood. There aren't specific tattoos to represent sisterhood.
The Roman Numeral symbol for 500 is the letter D. You would represent the number 510 as DX.
a long path would represent journey or maybe even a globe.