V. S. Apte, The Practical Sanskrit–English Dictionary. Look up any word of the Gita in Devanagari, IAST or Harvard-Kyoto, or browse the headwords letter by letter.
Entry यन्तृ
यन्तृyantṛa.Restraining, curbing, controlling.
[यम्-तृच्]
Restraining, curbing, controlling.
Guiding, directing. -Masculine
A director, governor, ruler.
A driver (as of an elephant, carriage etc.), coachman, charioteer; यन्ता गजस्याभ्यपतद् गजस्थम् R.7.37; अथ यन्तारमादिश्य धुर्यान् विश्रामयेति सः 1.54; Bhāg.8.11. 17; Ki.7.32; सव्योऽपि सानुनयमाकलनाय यन्त्रा Śi.