a. 不慈悲的, 无情的, 残忍的

[ adj ]
having or showing no mercy
<adj.all>
the merciless enemya merciless critic
gave him a merciless beating

Unmerciful \Un*mer"ci*ful\, a.
Not merciful; indisposed to mercy or grace; cruel; inhuman;
merciless; unkind. -- {Un*mer"ci*ful*ly}, adv. --
{Un*mer"ci*ful*ness}, n.