Fennel is a pale green plant with very fine, feathery leaves. The whole plant can smell a little like liquorice or aniseed. Cooks use the seeds to give a special taste to bread, sausage, and fish. One kind has a fat white bottom (Florence fennel) that people eat as a vegetable, raw or cooked — crunchy, a bit sweet. In Taiwan you will meet the seeds more often than the fat bulb. It is ordinary kitchen English, not slang. Though actually, the smell sits near star anise, and that is why learners mix them up. They are not the same plant. Fennel is the feathery green one (and its seeds); star anise is the hard brown star you drop into a soup.