Knowledge is information which when physically embodied in an environment tends to cause itself to remain so.
Examples of Knowledge:
The growth of Knowledge consists of correcting misconceptions in our theories. Ever since the Enlightenment this had happened through a tradition of criticism. New explanations are proposed, criticized, and then refined. Since the tradition of Conjecture and criticism has created all Knowledge and Progress it's absolutely imperative that we keep it. Free speech is critical. No idea should be beyond criticism.
The theory that all knowledge is derived from sense-experience (i.e. from experimentation). When empiricism was first introduced it played a positive role for Progress by providing a defence against traditional authorities and dogma. All claims of the supernatural now had to be backed up by hard evidence, which meant that 'provable' science superseded religious mysticism and superstition.
Finding faults in Knowledge creation or replication.
Moral philosophy is basically about the problem of what to do next–and, more generally, what sort of life to lead, and what sort of world to want. Morality is a type of Knowledge. This means that moral 'truths' can be discovered by the usual methods of reason, which are essentially the same as those of science (although there are important differences).
The misconception that there is nothing significant about humans (cosmically speaking) and anything claiming the opposite (e.g. sun revolves around the earth) is wrong. While this philosophy has been a useful rule of thumb to refute Anthropocentric explanations of the universe it is ultimately wrong because humans are Knowledge creating People (thus have infinite potential).
The misconception that the earth is a unique biosphere that humans are limited to, and that nature readily presents us with all our needs (food, shelter, water, etc). In reality earth never had our priorities in mind. Since the earliest times we had to create technology to survive. Even today, without such technology, we would only survive a few hours in say Oxford's winter.
The term has two almost opposite, but often confused, meanings: to provide someone with what they need, and to prevent things from changing. Homo-sapiens was never sustainable. No species is - 99% of them have gone extinct. Eventually the human-race will be, unless we choose otherwise, wiped out by some ice age, a meteor, a supernova, etc.
The only uniquely significant thing about humans vs other animals is our ability to create new explanations. We are universal explainers. In other words there is no problem that cannot, with sufficient Knowledge, be explained by a human.
A practice or lifestyle that cannot able to be maintained at the current rate or level. Often used in an environmental context: e.g. human population growth is not sustainable. In practice, nothing is sustainable. Problems are inevitable and eventually one big enough will come along to prevent you from sustaining an existing course of action.