Neologism is generally defined as "coining of a new word", "a new word, meaning, or phrase," and "new senses of existing words." It is rougly a synonym of the term coinage.
Here is a few examples of the English neologisms by Paul McFedries:
thirty-second surfer: a person who channel surfs during a TV commercial.
corplaining: griping, grousing, and otherwise complaining about the corporation you work for.
agressocracy: a society in which the most aggressive members rise to the top.
More examples from another source, "incompetech", are:
treeware: a hacker slang for documentation or other printed material, such as books.
blamestorming: sitting around in a group, discussing why a deadline was missed or a project failed, and who was responsible.
Below a few examples of the ASL neologisms excerpted from a poem illustrates how the poet and literary artist used neologism and nonce words (used only once). Neologism and nonce words (used only once) are commonly used in sign language poetry.
First, understand the context of the poem (as seen in the section Literature + Art) which was interpreted from William Blake's verse:
To see a world in a grain of sand
And heaven in a wild flower
Hold infinity in the palm of your hand
And eternity in an hour.
-- William Blake (1757-1827) from "Auguries of Innocence"
The regular ASL word for "forever" is as follows:
In her interpreted poem, the poet created a neologism for the part infinity in sense of the space rather than time for the line "Hold infinity in the palm of your hand." The signer uses the space in front of her. [below]
For the line "And eternity in an hour," the poet created another neologism for the part "eternity". She uses the word "forever" in both directions -- the ever past and the ever future. [below]
Even though these neologisms or new words are immediately created in poetry in sign language, they might be likely not used in daily conversation. In this case, these neologisms can be considered a nonce word, a word invented on the spot and used once. But, if more people start using it, then it may get promoted to a neoglogism.
Jolanta Lapiak. "William Blake's Poem" Handspeak in Literature + Art section. http://www.handspeak.com .
Paul McFedries. "My Neologisms," Word Spy. http://www.wordspy.com/diversions/neologisms.asp .
Also see word borrowing in sign language.
compounding and blending in sign language.