If someone or something weighs a particular amount, this amount is how heavy they are.

If you weigh something or someone, you measure how heavy they are.

If you weigh the facts about a situation, you consider them very carefully before you make a decision, especially by comparing the various facts involved.

If you weigh your words, you think very carefully before you say something.

If a problem weighs on you, it makes you worried or unhappy.

Something that weighs heavily in a situation has a strong influence or important effect on it.