You can say 'cross my heart' when you want someone to believe that you are telling the truth. You can also ask 'cross your heart?' when you are asking someone if they are really telling the truth.

Your heart is the organ in your chest that pumps the blood around your body. People also use heart to refer to the area of their chest that is closest to their heart.

You can refer to someone's heart when you are talking about their deep feelings and beliefs.

You use heart when you are talking about someone's character and attitude towards other people, especially when they are kind and generous.

The heart of something is the most central and important part of it.

The heart of a place is its centre.

A heart is a shape that is used as a symbol of love: ♥.

Hearts is one of the four suits in a pack of playing cards. Each card in the suit is marked with one or more symbols in the shape of a heart.

A heart is a playing card of this suit.

If you feel or believe something with all your heart, you feel or believe it very strongly.

If you say that someone is a particular kind of person at heart, you mean that that is what they are really like, even though they may seem very different.

If you say that someone has your interests or your welfare at heart, you mean that they are concerned about you and that is why they are doing something.

If someone breaks your heart, they make you very sad and unhappy, usually because they end a love affair or close relationship with you.

If something breaks your heart, it makes you feel very sad and depressed, especially because people are suffering but you can do nothing to help them.

If you know something such as a poem by heart, you have learned it so well that you can remember it without having to read it.

If someone has a change of heart, their attitude towards something changes.

If something such as a subject or project is close to your heart or near to your heart, it is very important to you and you are very interested in it and concerned about it.

If you can do something to your heart's content, you can do it as much as you want.

If you say something from the heart or from the bottom of your heart, you sincerely mean what you say.

If you want to do something but do not have the heart to do it, you do not do it because you know it will make someone unhappy or disappointed.

If you believe or know something in your heart of hearts, that is what you really believe or think, even though it may sometimes seem that you do not.

If your heart isn't in the thing you are doing, you have very little enthusiasm for it, usually because you are depressed or are thinking about something else.

If you lose heart, you become sad and depressed and are no longer interested in something, especially because it is not progressing as you would like.

If your heart is in your mouth, you feel very excited, worried, or frightened.

If you open your heart or pour out your heart to someone, you tell them your most private thoughts and feelings.

If you say that someone's heart is in the right place, you mean that they are kind, considerate, and generous, although you may disapprove of other aspects of their character.

If you have set your heart on something, you want it very much or want to do it very much.

If you take heart from something, you are encouraged and made to feel optimistic by it.

If you take something to heart, for example someone's behaviour, you are deeply affected and upset by it.