Like onomatopoeia, but visual

Onomatopoeia is defined as:

The formation of a word from a sound associated with what is named (e.g. cuckoo, sizzle).

Is there a term for describing the formation of a word from a shape/image associated with what is named; and/or a word so formed?

The oldest word like that I can think of would be

delta

A triangular tract of sediment deposited at the mouth of a river, typically where it diverges into several outlets:

Origin: Mid 16th century: originally specifically as the Delta (of the River Nile), from the shape of the Greek letter

The newest I can think of would be XOXO (O and X are crude visual representations of a hug and a kiss respectively). I know it's arguably not a word, still...

Then we have words like U-turn, T-bone and V-neck, which are named after the shape of the letter (as against words like X-rays, A-team and B-boying)

Is there any term that describes words like this?

PS - If there isn't, neologisms are welcome in comments.

The word phenomime can be used for words that act like onomatopoeia (also known as phonomimes) for non-auditory sensory stimuli (the other four senses). They are quite common in Japanese, which also has psychomimes (words that act like onomatopoeia for emotions, thought processes, states of mind).

• Phonomimes use word sounds to represent auditory stimuli, such as a bark, a meow, or a honk.
• Phenomimes use word sounds to represent non-auditory stimuli, such as a flash, a twinkle, or a grope.
• Psychomimes use word sounds to represent psychological stimuli, such as the pitter-pat of a quickened heart, dizziness, or reluctance.

They are simply called shape words.

It is mentioned in Jeff Miller's Collection of Word Oddities and Trivia; and coined by Dan Tilque:

Dan Tilque has compiled a list of what he calls "shape words," terms in English that are composed of a single letter and a word (or two), where the letter describes the shape of the object.

He attempts to show one word for each letter of the alphabet, but several letters are missing. His list: A-frame, C-clamp, D ring, f-hole, F clamp, G clamp, H hinge, I beam, J-bar lift, K truss, K-turn, L square, M roof, O-ring, P trap, S curve, T-shirt, T-intersection, T-bone, T-square, U-turn, V neck, W-engine, X truss, Y theodolite, and Z bar. [Mark Brader and Phil Jacknis added to Dan's list.]

Language Log mentions the same source and adds that formal documents used such terms freely. It is also mentioned that other languages have similar words. For example, in Chinese, there are shapes that correspond to Chinese characters.

十字路口, a "十 intersection", refers to a four-way intersection (or just any intersection). The phrase is based entirely on the shape of the character, and not the meaning (十 means ten in Chinese).

_{Further details for Chinese characters: https://chinese.stackexchange.com/questions/1805/words-referring-to-the-shape-of-chinese-characters}

It is also described as using letter shapes as analogies in A Biography of English Language by C.M.Willmard:

The closest I can come for

a word from a shape/image associated with what is named

is

Hieroglyphyc from

Hieroglyph: a picture or symbol representing an object, concept, or sound

or, even simpler, you could say that the written form of the word is figurative

representing by means of an emblem, likeness, figure, etc

(painting, sculpture) of, relating to, or characterized by the naturalistic representation of the external world

For example, a U-turn is in the shape of what it is represented.