Yantra means

SB Canto 4

The word yantra means "carriage."

SB 4.26.1-3, Purport:

The word yantra means "carriage." The body is given by material nature, and the driver of that body is Paramātmā, the Supersoul. The living entity is seated within the chariot. This is the actual position.

SB Canto 6

Yantra means a machine, such as an automobile.

SB 6.1.31, Purport:

"The Supreme Lord is situated in everyone's heart, O Arjuna, and is directing the wanderings of all living entities, who are seated as on a machine, made of the material energy." Yantra means a machine, such as an automobile. The driver of the machine of the body is the individual soul, who is also its director or proprietor, but the supreme proprietor is the Supreme Personality of Godhead.

Bhagavad-gita As It Is Lectures

Yantra means machine.

Lecture on BG 2.15 -- Mexico, February 15, 1975:

Yantra means machine. So just like in our car we can travel here and there, similarly, on this machine of body we can go anywhere.

Kṛṣṇa is supplying these toy bodies Yantra, yantra means machine.

Lecture on BG 2.21-22 -- London, August 26, 1973:

Kṛṣṇa knows your desire, that if you want still to enjoy this material world, "All right, enjoy." So for enjoying different kinds of enjoyment, we require different kinds of instrument. So Kṛṣṇa prepares you, so kind, "All right." Just like the father gives a toy, the child wants a motorcar. "All right, take a toy motorcar." He wants a engine, he wants to become a railway man. Now these kinds of toys were(?) there. Similarly Kṛṣṇa is supplying these toy bodies Yantra, yantra means machine. This is a machine. Everyone understands this is a machine.

Lecture on BG 13.1-2 -- Miami, February 25, 1975:

Yantra means machine. So we are seated on this machine. This is the knowledge.

Srimad-Bhagavatam Lectures

This body is a yantra, car, mechanical car.

Lecture on SB 1.2.6 -- New Vrindaban, September 5, 1972:

I am not this body. This is a vehicle. Just like we ride on a car, drive car, so I am not this car. Similarly, this is a yantra, car, mechanical car. Kṛṣṇa or God has given me this car, I wanted it.