improvise v. ad-lib

[tonguingaround]

Hi there
I d like to know if "improvise" and "ad lib" are interchangeable.
Thanks in advance

Example
The show is not scripted - the actors have to improvise.
The show is not scripted - the actors have to ad lib.

 

[wandle]

They are equivalent in the above context: but not in all contexts.

'Ad lib' also has an adverbial use ('as you like'):
'With this construction system, you can include further modules ad lib.'

 

[Biffo]

In fact I argue that 'to ad lib' the verb is actually an abbreviation of "to improvise ad lib" which means "to improvise at one's pleasure".

For example, in music, the composer could ask the performer to 'improvise for eight bars' in contrast to 'improvise ad lib' which would indicate 'improvise for as many bars as you wish'.

The use of 'ad lib' as an independent verb has blurred the distinctions so now the two can mean the same depending on circumstance.

 

[Beryl from Northallerton]

In the given context, one of the performance being unscripted by design, I would say the actors are called upon to improvise. I would reserve ad-libbing for a situation in which there was an unscheduled departure from the script, e.g. an actor forgets his lines, or simply needs to fill up time.

 

[pob14]

Beryl's description is the way the phrases are used in the theatre.

"Improvisation," or simply "improv," is the situation whter there is no script and the actors create the entire scene as they go.

To ad lib is to create one or a few lines, either in the situations Beryl described, or when the actor thinks (usually incorrectly) that he can make up better lines than the writer did.