An idiom is a commonly used expression whose meaning does not relate to the literal meaning of its words. (for example They went out to paint the town red.)
A clause that interrupts the flow of a sentence. (for example, He kept insisting-what other option did he have- that he had taken no part in writing the comments.)
The use of words to convey a meaning that is the opposite of its literal meaning.
Verbs that do not follow the simple system of adding “d” or “ed” to the end of the word to form the past tense (for example, buy-bought, sing-sung)