Some words occur together naturally. This is called beyondBinomialsChunkscollocatescollocationidiomlexemesmeaningnounsemi- and the words that come together are called beyondBinomialsChunkscollocatescollocationidiomlexemesmeaningnounsemi-.
For example, adjective + beyondBinomialsChunkscollocatescollocationidiomlexemesmeaningnounsemi-: flat landscape, painful toothache etc.
There are some phrases in English which are known as fixed or beyondBinomialsChunkscollocatescollocationidiomlexemesmeaningnounsemi-fixed. Usually, these are beyondBinomialsChunkscollocatescollocationidiomlexemesmeaningnounsemi- which are formed of more than one word but which have a single beyondBinomialsChunkscollocatescollocationidiomlexemesmeaningnounsemi-.
Usually, we cannot understand an beyondBinomialsChunkscollocatescollocationidiomlexemesmeaningnounsemi- by knowing the meaning of the individual words.
beyondBinomialsChunkscollocatescollocationidiomlexemesmeaningnounsemi- are pairs of words which often come together and are fixed.  For example, above and beyondBinomialsChunkscollocatescollocationidiomlexemesmeaningnounsemi- (= more than)
beyondBinomialsChunkscollocatescollocationidiomlexemesmeaningnounsemi- can be learned and used as if they were single language items but they are different from idioms.