Question

Name of Negative Acceleration
Negative acceleration is called as what?

Answer 1

Name of negative acceleration is $\bf{retardation}$.

Actually, Acceleration is rate of change of velocity.
I mean, acceleration = change in velocity/time taken
Or, acceleration = (final velocity - initial velocity)/time taken
now, when acceleration is negative then, initial velocity is greater than final velocity. Means, body decreases their velocity in case of negative acceleration.
that's why it is known as retarding motion.

Answer 2

ᴛʜᴇ ɴᴀᴍᴇ ᴏғ ɴᴇɢᴀᴛɪᴠᴇ ᴀᴄᴄᴇʟᴇʀᴀᴛɪᴏɴ ɪs ᴅᴇᴄᴇʟᴇʀᴀᴛɪᴏɴ.☺️

✨ᗯᕼᗴᑎ Tᕼᗴ ᐯᗴᒪOᑕITY Oᖴ ᗩ ᗷOᗪY ᗪᗴᑕᖇᗴᗩՏᗴՏ, Tᕼᗴ ᗩᑕᑕᗴᒪᗴᖇᗩTIOᑎ IՏ Iᑎ OᑭᑭOՏITᗴ ᗪIᖇᗴᑕTIOᑎ Oᖴ ᐯᗴᒪOᑕITY ᗩᑎᗪ ᕼᗴᑎᑕᗴ ᗩᑕᑕᗴᒪᗴᖇᗩTIOᑎ IՏ ՏᗩIᗪ TO ᗷᗴ ᑎᗴᘜᗩTIᐯᗴ ᗩᑕᑕᗴᒪᗴᖇᗩTIOᑎ.✨

Ⓐ︎Ⓒ︎Ⓒ︎Ⓔ︎Ⓛ︎Ⓔ︎Ⓡ︎Ⓐ︎Ⓣ︎Ⓘ︎Ⓞ︎Ⓝ︎= final velocity(v)- initial velocity (u)/ time(t).