A woman supporting her own breasts by use of one or both of her upper limbs. This is usually done to:

• Cover the nipples and areola.
• post #53545
• post #58036
• Also applies to women lifting their breasts with their arms or hands in order to squeeze them or show more cleavage.
• post #68339
• post #64568

Few more examples at post #9394 and post #10433.

This tag shouldn't be confused with breast_grab, where a woman's breasts are being held by another entity in a groping fashion.

(Partially copied from Danbooru)