There is a word missing from the English language. We all know about onomatopoeia, the naming of a thing or action by a vocal imitation of the sound associated with it according to Merriam-Webster online. Typical examples are buzz or hiss.
I would like a similar word for naming things with letters similar to how they look. For example, at the end of a letter people often write ooo or xoxo. The x means kiss and is clearly onomatopoetically derived. The o symbolizes a hug, derived from the circle that arms and torso make when hugging someone. It is not onomatopoetic, as there is no sound intrinsic to hugging. Rather, the shape of the action is similar to the shape of the symbol.
Another example is the sexual position known as the 69, thus named because the symbol for it resembles the sexual position itself.
Yet another example is corner couches, where one end of the couch is longer than the other. Such couches are sometimes referred to as L shaped, when the right end (from the vantage of the coffee table) is longer than the left end. It has an L shape.
Perhaps a final example is the Arabic numbers that we all use on a daily basis. According to some sources, originally the symbols for the numbers from 0 to 9 had from 0 to nine angles. Thus the shape of the digit was directly connected to what it meant.
The word letterform, referring in general to the form of letters, already exists. I suggest that the definition of letterform be expanded to also mean the naming of a thing or action by letters imitating the shape associated with it.