Any
substance,
chemical, or
tool used for
cleaning. This can be anything from
plain water to
muriatic acid. Usually the term conjures up for me a
bucket filled with various
spray bottles of various
colors, and
sponges and
rags.
Some cleaning supplies are quite toxic when ingested. In fact, they nearly all are, since they're based on soaps, detergents, ammonia, or bleach, or some combination. Bases like these in large concentrations will kill you. Other cleaning supplies contain phenolic compounds that are surface germicides which also would be toxic when ingested. Even environmentally friendly cleaning supplies are still usually toxic--their advantage is that they're usually quickly biodegradable and leave little pollution.
This is why I don't clean.