[...] "idiomatic compounds" [...] acquire part of their semantic content via "meaning transference rules" [...]. - Downing (2004), a pag.182
As an example of an "idiomatic compound", Li cites the form "June bug". He contends that this is idiomatic in that it serves as the same of a certain bug, regardless of the month in which the bug actually appears. - Downing (2004), a pag.204