6) What does “validation/validity” mean? What does “significance” mean? What does “reliability” mean? What does “relevance/relevant” mean?

Validation is that process is checked in order to ensure that it works without problem. Validation is to prove something to be sound or logical.
References:
http://en.wikipedia.org/wiki/Validation
http://www.answers.com/topic/validation?cat=technology


Significance is the quality in certain criteria. The significance of something implies that it has the importance.
References:
http://users.skynet.be/cpso/engterm2.htm
http://www.seslisozluk.com/?word=significance


Reliability is that system or person suitably performs its required functions under given circumstances. An other words, system or person does given work in expected style.
References:
http://www.answers.com/topic/reliability-1?cat=biz-fin
http://en.wikipedia.org/wiki/Reliability

Relevant is connection with the subject at issue. Relevance provides evaluating the quality of information with matching.
References:
http://dictionary.die.net/relevant
http://lib.nmsu.edu/instruction/healthsci/vocab.html#R