The definition of 40 is the number that comes after 39 and before 41. It is an even number, and it can be divided evenly by 2, 4, 5, 8 and 10. Forty has been used as a symbol in many cultures throughout history to represent a variety of concepts from life cycles to spiritual enlightenment.

In numerology forty represents completion or fulfillment – the end of one cycle but also the beginning of another; it is seen as being both an ending point and a new starting point at once. This idea ties into its symbolic use across various religions which often see forty days or nights representing periods for reflection on past actions while looking forward with anticipation towards future possibilities.

In some ways 40 can be thought about like 0 – they are both round numbers that denote fullness or emptiness depending on how you look at them; 0 implies nothingness whereas 40 implies completeness due to all its factors coming together perfectly in harmony with each other (2x2x5).

As such this makes 40 quite powerful when considering any kind of transformation process either physical emotional mental etc., since it signals not only a change but also potential growth opportunities ahead if embraced fully!