As we know that even signal is that type of signal which exhibits symmetry in the time domain . This type of signal is identical about origin . Mathematically an even signal must satisfy following condition
for continuous time signal x(t) = x(-t)
for a discrete time signal x(t) = x(-n)

Similarly , an odd signal which exhibits anti-symmetry.
This type of signal is not identical about origin.
Actually , the signal is identical to its negative. Mathematically an odd signal can be represent as :
for continuous time signal x(t) =-x(-t)
for discrete time signal x(n) =-x(-n)