headforemost

from The Collaborative International Dictionary of English v.0.48

Headfirst \Head`first"\ (h[e^]d"f[~e]rst`), Headforemost
\Head`fore"most`\ (h[e^]d`f[=o]r"m[=o]st`), adv.
   With the head foremost; -- of motion.
   [1913 Webster]