Terminal velocity is usually defined as the

The consent speed of something freely falling object eventually reaches the resistance of the medium through which it is falling prevents further acceleration. 

Using the word "Terminal" which means end, we can conclude that, in a nutshell, terminal velocity is when an object reaches a speed where it cannot go any faster. For example, if you jumped of the Empire State building, before you went "KURSPAT!" on the pavement below, you would enter Terminal Velocity. Your fall off the Empire State building would also be "terminal". eh? Hahahaha never try a physics joke.

Initial velocity,  u = 4.9 m/sfinal velocity = v m/sinitial height,  h₁ =  245 m    final height, h₂ = 0a = -9.8  m/s²time taken = t secondss = ut + 0.5at²⇒  (h₂-h₁) = ut + 0.5at²⇒  0-245 = 4.9t + 0.5×(-9.8)×t²⇒ -245 = 4.9t - 4.9t²⇒ 4.9t² -4.9t -245 =0solving it, we get   t = 7.59sv  = u +  at = 4.9 -9.8×7.59 = 4.9 - 74.38 = -69.48 m/svelocity is  69.48 m/s downward