A single stage in a chemical reaction. For example, the addition of hydrogen chloride to ethene involves three steps:
Chemical Engineering
A discrete activity or stage within an overall process or chemical reaction.
Geography
An abrupt, but short, break of slope, especially in a glacial trough. Steps tend to be smoothed and striated upstream, as the ice grinds the bedrock, and craggy downstream, because of quarrying; see R. Huggett (2003).