inner ends of the eyebrows; the part of the eyebrows near the middle forehead
Refers to the area where the eyebrows meet the bridge of the nose. Often used in expressions about frowning or concentrating.
When he is deep in thought, he always furrows the inner ends of his eyebrows.
The area near the inner ends of my eyebrows itches.
Compound of 眉 (まゆ, 'eyebrow') and 頭 (かしら, 'head' or 'top'), referring to the 'head' or inner end of the eyebrow.