Of a number of people walking, or especially marching, synchronously, so that that footfalls occur at the same time.

(idiomatic) Agitated and anxious. / (colloquial) Messed up.

(information science) An indexing algorithm which indexes a document based on the keywords being searched for.

In operation. / In combat.

(idiomatic) To be fooled; to fall for. / (idiomatic) To be unofficially fostered.

in wine, there is truth

A warning of an imminent explosion in a confined space, especially a grenade or blasting charge. / (slang) A generalized warning that something is about to happen.

(linguistics, anthropology) The style of speech and manners which are to be observed between an Australian aboriginal man and his mother-in-law (i.e. wife's mother). Depending on the particular people, this can go so as far as an entirely separate vocabulary of words.

(idiomatic) A problem or difficult issue that is very obvious, but is ignored for the convenience or comfort of those involved.

(idiomatic, Britain, Ireland, humorous, informal) To become overwrought or unnecessarily upset over a trivial matter.