Definitions:
a number of people or things that are located, gathered, or classed together

a set of elements occupying a column in the periodic table and having broadly similar properties arising from their similar electronic structure.

a set of elements, together with an associative binary operation, which contains an inverse for each element and an identity element.

(in systemic grammar) a level of structure between clause and word, broadly corresponding to phrase in other grammars.

put in a group or groups