Lying is a communication intended to deceive or mislead. Lies of omission, and of misdirection, are lies.
One effort to limit the extent of "lying" is to try to distinguish between overt and implicit deceptive language. The assumption here is that the actual words are what constitute lying, and the effort to mislead through innuendo, skewed facts, or changing emphasis on workds or syllables -- is somehow NOT linguistic communication. But linguistic communication, of course includes both overt words and innuendo, and both syllabic and word emphases.
Communication is also often non-linguistic. Pointing to oneself, if a party is asked to identify themselves -- if one is not the party requested, is deliberate deceptive miscommunication. Whenever one knows that others are reading one's signals, then misleading them by sending out false signals is a deliberate effort to mislead.
It is not just humans who lie. I had a dog, who after being fed by my wife, would often come up to me and look mournful and hungry -- trying by misdirection to get double dinner. Both predator and prey animals will make feints in one direction or another, to mislead their adversary.
The best analysis of lying I have seen was from libertarian thought, and it treated lying as a degradation of the common currency of communication we all need to access the world and society, hence all miscommunication of any kind was harmful to all. This is treating humans as a primarily social animal, who rely upon the marketpalce of ideas to be functional to gain reasonable information -- and subversions of that marketplace serve as a parasitic behavior that degrades its value to all.