I am looking for a word to describe a computer system or program or software that allows more erroneous inputs while still running fine instead of hanging easily.
I was thinking of "forgiving" but thats more for people not for systems, no?
e.g. This is a _______ system
This software is more _______
"Robust" is sometimes used to convey the system behavior you describe, with the positive connotation.
For example:
Despite what user input comes its way, the program does not crash. It is very robust.
flexible, tolerant. But you may be better off using two words or a compound word. I'd use fault-tolerant.
For example:
Even though the user formatted the date incorrectly, it handled the mistake gracefully. It is fault-tolerant.
This is a resilient system.
This is a good word to talk about fault-tolerant system.
I can't believe that nobody has submitted...
In modern English usage, the informal term idiot proof or foolproof describes designs which cannot be misused either inherently, or by use of defensive design principles. The implication is that the design is usable even by someone of low intelligence who would not use it properly.
Granted, it is somewhat course and insulting but your question states
I am looking for a word to describe a computer system or program or software that allows more erroneous inputs while still running fine instead of hanging easily.
Anyone having dealt with computer users long enough knows that "erroneous inputs" can translate to "Something odd happened and there were lots of windows popping up and I just kept clicking things. Fix it!"
This is a robust system
This software is more robust
However, I think jiggunjer's suggestion of fault-tolerant is even better, notwithstanding your qualms about offending your customer. As he/she says, it's an industry term which your customer should be able to swallow without flinching.
In my opinion, care is needed to ensure that being polite to a customer does not turn into pandering.
Specifically on the subject of input, Jon Postel said:
TCP implementations should follow a general principle of robustness: be conservative in what you do, be liberal in what you accept from others.
This principle is paraphrased and misquoted all over the place, with words like "lenient", "generous", "tolerant" in place of "liberal"[*]. All of these mean the system allows variety in what input it accepts and responds to.
However, he was mostly talking about not treating input as erroneous, and whether to return errors, refuse connections, etc, or just to work as far as possible. You're talking about not hanging. A system should generally not hang unless explicitly instructed to loop forever. So if in your case the important thing to convey is that it doesn't hang/crash, you could say the system is "robust". Or you could talk about what it isn't: "faulty", "buggy", "broken". You don't generally want to tell the outside world that your system is bug-free, because generally it isn't, but internally or when talking about someone else's system you can use that kind of language.
[*] No political statement[**] intended
[**] Maybe a little bit.
I suggest that the adjective "permissive" comes closest.
The dictionary meaning is generally along the lines of "Allowing or characterised by great or excessive freedom of behaviour".
lenient is the word. 'fault tolerant' is a technical word, not really a word found in English parlance. For example, you can say 'English teacher is lenient', not 'English teacher is fault tolerant'. If a 'document' writing software does not check for, say grammar or spelling, it is not a fault tolerant software :D
The 'robustness principle' (aka 'Postel's Law' after Jon Postel) says (in respect of computer programs):
Be conservative in what you do, be liberal in what you accept from others (often reworded as "Be conservative in what you send, be liberal in what you accept").
Okay this is how I see it:
Robust, in the sense that it tolerates errors by the machine itself/external component, the source of the error is usually internal, possibly by the software itself(it's components), maybe when communicating with an external API. In any case it tolerates machine-machine errors possibly created by faulty initial design.
Fool-proof : Something that tolerates faulty/out of range input from an external user, either by alerting him to fix it, or by implementing a strategy to understand the input it was given - in any case it does not crash.
Close to this is the term Graceful Degradation. This is a term frequently used in software development to describe a system that doesn't die horribly the moment something goes wrong.
Usually more used for when prerequisites aren't met, but could apply here too.
In software engineering, we use the term save-fail as a contrast to fail-save.
How about "User friendly"? Advertising types use it frequently. ;-)
I was thinking of "forgiving".. It's the first word I thought of for your system.