words made from two separate words (headache)

a word or phrase borrowed from another language by literal word-for-word or root-for-root translation. (I very like ... ).

mixing words to make a new one (brunch)

has an opposite meaning

words which are frequently used together (sleep peacefully\well\badly)

two or more words join together and TOGETHER act as if they are one unit of meaning (run out of\ not sleep a wink)

prefixes and suffixes that are added to base words

the smallest meaningful unit in a language (root\affixes\inflections

a group of words that has a special meaning that is different from the ordinary meaning of each separate word. For example, ‘under the weather’ is an idiom mean

an idea or feeling that a word suggests, which is more than just its meaning. (pig-headed).