a second

An unknown unit of measurement.

"I need to move the car back a second."

"You need to adjust the width a second."

Second

The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom (at 0 Kelvin).

The second has an interesting definition!

seconds

Filling your plate with food for the second time

He was still hungry, so he went back for seconds

second

The duration of 9,192,631,770 periods of radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 132.91 atom.

I'll be two seconds...

Secondively

In addition to a point made earlier.

"And secondively, I know you are the big marriage expert...Oh I'm sorry, I forgot...your wife is dead!" - Tobias Fünke

seconded

when you agree to someones opinion.

Cherry coke is the best soda of all time!

- seconded

second

A length of time that is very-under-exaggerated.

<Killer> Hey there.
<Spiller> Hi, I'll be back in a second.
<Killer> Okay.
*** 20 minutes later ***
<Killer> ...
<Spiller> I'm back.
<Killer> Where were you?
<Spiller> Hang on, back in a second.
*** Killer is offline ***