a. 仪器的, 器具的, 可作为手段的

[医] 器械的

[经] 仪器(器械)误差

Instrumental \In`stru*men"tal\, a. [Cf. F. instrumental.]
1. Acting as an instrument; serving as a means; contributing
to promote; conductive; helpful; serviceable; as, he was
instrumental in conducting the business.

The head is not more native to the heart,
The hand more instrumental to the mouth. --Shak.

2. (Mus.) Pertaining to, made by, or prepared for, an
instrument, esp. a musical instrument; as, instrumental
music, distinguished from vocal music. ``He defended the
use of instrumental music in public worship.'' --Macaulay.

Sweet voices mix'd with instrumental sounds.
--Dryden.

3. (Gram.) Applied to a case expressing means or agency; as,
the instrumental case. This is found in Sanskrit and
Russian as a separate case, but in Greek it was merged
into the dative, and in Latin into the ablative. In Old
English it was a separate case, but has disappeared,
leaving only a few anomalous forms.

{Instrumental errors}, those errors in instrumental
measurements, etc., which arise, exclusively from lack of
mathematical accuracy in an instrument.