A thick bra, loose shirt, or other protective covering to prevent a woman'snipples or areolas from showing.
Since the air-conditioning in the hotel conference room was set to "iceberg", she decided to dart back up to her room for a sweater to use as mammoflage during her presentation.
The practice of concealing or diminishing the appearance of ones breasts. Also anything intended to do so, especially a tight band of cloth wrapped around the chest (also known as binding).