Breast - Vine's Expository Dictionary of New Testament Words
Breast
[ 1,,G4738, stethos ]connected with histemi, to stand," i.e., that which stands out, is used of mourners in smiting the "breast," Luke 18:13; Luke 23:48; of John in reclining on the "breast" of Christ, John 13:25; John 21:20; of the "breasts" of the angels in Revelation 15:6.
[ 2,,G3149, mastos ]
used in the plural, "paps," Luke 11:27; Luke 23:29; Revelation 1:13, AV, is preferably rendered "breasts," in the RV.