a. 左的, 使用左手的, 左旋的

[医] 左侧的; 左利的, 善用左侧器官的

Sinistral \Sin"is*tral\, a.
1. Of or pertaining to the left, inclining to the left;
sinistrous; -- opposed to {dextral}.

2. (Zo["o]l.) Having the whorls of the spire revolving or
rising to the left; reversed; -- said of certain spiral
shells.

counterclockwise \coun"ter*clock"wise\ adj. & adv.
in the opposite direction to that in which the hands of a
clock rotate, as viewed from in front of the clock face; --
of rotatory motion or spiral direction. Opposite of
{clockwise}, or {right-handed}

Note: [Narrower terms: {sinistral} {levororotary,
levorotatory}]

Syn: left-handed.
[PJC]