The part of a snare drum that has several small strings or catgut threads strung tightly across it. The snare head is not struck but makes a distinctive resonant sound, the timbre of which can be changed by tightening or loosening the snares.
Usages: "Their drums...received several small shot in the batter heads, which they went through, but immediately struck out again by the Rims, and touch'd not the snare heads." (1704, E. SMITH, _Athenian Oracle_ III. 423, cited in OED)
"‘Snares’...consist of a number of gut or wire strings stretched across the lower skin or ‘snare head.’" (A. C. BAINES, _Musical Instruments_ xiv. 335, 1961, cited in OED)