1620s, anslaight, somehow from or on analogy of Dutch aanslag "attack," from Middle Dutch aenslach, from aen "on" (see on) + slach "blow," related to slaen "slay." Spelling influenced by obsolete (since c. 1400) English slaught (n.) "slaughter," from Old English sleaht (see slaughter (n.)). No record of its use in 18c.; apparently revived by Scott.
