When two words are amalgamated (or "smushed together") leading to the omission of certain sounds, it is commonly termed a contraction.

 A contraction is a word or phrase that's been shortened by dropping one or more letters or sounds. In written form, an apostrophe often represents the missing letters.

Examples:

"can't" from "cannot"
"they're" from "they are"
"I'm" from "I am"
"let's" from "let us"

However, not all spoken contractions are commonly represented with apostrophes in writing. "Wanna" for "want to" and "gonna" for "going to" are examples of informal spoken contractions.

In addition to contractions, there's also a term called blend. A blend is formed by merging two separate words into one. However, blends are different from contractions. Contractions typically involve omitting specific letters or sounds, whereas blends combine portions of each word. Examples of blends include "brunch" (from "breakfast" + "lunch") and "motel" (from "motor" + "hotel").

American Sign Language (ASL) does have its own form of contractions, although it's important to remember that ASL is not a signed version of English. Its grammar, syntax, and vocabulary are distinct. Nevertheless, ASL does have some signs that are similar in function to English contractions, in that they represent shortened or combined forms of longer expressions.

Here are some examples:

I DON'T KNOW: There's a single sign in ASL that communicates the entire English phrase "I don't know." Instead of signing each word separately, a signer shrugs the shoulders, opens the hands palms up, and shakes the head slightly.

WHAT-DO: This sign is often used to mean "What are you doing?" It's a combination that's quicker than signing each word of the phrase separately.

TRUE-BIZ: This is a sign that means "really" or "seriously," effectively blending the concept of "true" and "business."

MOTHER-FATHER: While not exactly a contraction, it's worth noting that some signs can be sequentially combined in a way that's more efficient. For instance, the sign for "mother" immediately followed by the sign for "father" is a common way to refer to parents collectively.
 

DON'T WANT: This is expressed with a single sign in ASL. The motion begins near the chin and moves outward, indicating rejection or refusal.

NOT-YET: Instead of signing "NOT" followed by "YET," ASL users often use a single sign that communicates the concept of "not yet."

DON'T-LIKE: Rather than signing "DON'T" and then "LIKE" separately, there's a single sign that conveys the sentiment of disliking something.

DON'T-MIND: This phrase can be conveyed with a sign that blends the concepts of "don't" and "mind."

Just like in spoken languages, these "contractions" or combined signs can result from the need for efficiency, the evolution of cultural norms, or other linguistic influences. They might not be contractions in the same sense as English contractions, but they serve similar communicative purposes in ASL.

Also see: reversal of orientation for negation