I'm really not sure how, under that definition, it could be reasonably argued that he wasn't technically lying. Unless you think that the definition allows Lewinsky to have sexual relations with him (by giving him head) while he wasn't having sexual relations with her. Even so, the numerous other contact (the cigar, etc. It's been awhile since I read the Starr Report) would certainly constitute sexual relations.
In addition, Lewinsky's testimony may not be enough (her stained dress on the other hand....) but Clinton hardly had a legal right to do what he did: offer a prepared statement that his conduct was "inappropriate" and then refuse to answer more detailed questions. Really, I would invite a normal citizen to try this tactic of offering a prepared, vague statement and then refusing to answer other questions.
The legal definition of sexual relations as defined for the purpose of the deposition. I think it was something along the lines of "giving or receiving contact with the intent to sexually gratify" or something like that
I'm pretty sure it was this: "contact with the genitalia, anus, groin, breast, inner thigh, or buttocks of a person with an intent to arouse or gratify the sexual desire of any person." I'm not saying he wasn't lying, but that an argument could be made that he wasn't technically lying. In addition, Lewinsky saying they had sexual relations is not sufficient to prove perjury.