Putting two objects together is consider summing them. Summing mathematical terms is considered addition because you are adding another term or number to another.

It generally refers to any item of a series of items that are added together (or subtracted - in Algebra, subtraction can be seen as a special case of addition). For example, in a + b, "a" is a term; so is "b". In x2 + 7x + 5, x2 is one term, 7x is another term, and 5 is a third term.

Sequencing of events is another term for putting things in chronological order. This is the act of putting events together in the order that they happened.

Photosynthesis is the term used to describe how green plants or bacteria use light energy to convert water and carbon dioxide into sugar. I believe it comes from two Greek words - for light and putting together or synthesising.