Yes, contractions are typically included in dictionaries, especially in English dictionaries. They are categorized as informal language but are nevertheless recognized as valid words and listed with their meanings to help users understand their usage.
No, they're not part of the official Scrabble dictionary.
contractions
contractions come after non-contractions: Aunts Aunt's
Umm. . . contractions.
The strongest indication that contractions are occurring in association with true labor is that the contractions begin to occur at regular intervals. This is contrary to Braxton-Hicks contractions, which are spontaneous, random uterine contractions that do not occur with actual labor.
eccentric and concentric contractions
Peristalsis is the term for the rhythmic contractions of the esophagus. These wavelike contractions move food toward the stomach.
Isotonic contractions. This happens when the muscle shortens as it contracts
Four contractions with "you" in them are:You're - You areYou'd - You would or You hadYou'll - You willYou've - You have
Contractions are don't, didn't, won't, etc...
Isometric muscle contractions happen when the muscle stays the same length, concentric contractions occur when the muscle shortens, and eccentric contractions occur when the muscle lengthens.
Tonic muscle contractions are sustained and steady, while phasic muscle contractions are brief and intense. Tonic contractions last longer and have a lower intensity, while phasic contractions are shorter in duration but have a higher intensity.