(music) A soloist playing with a band or group of which he is not a regular member. / (MLE, derogatory) Somebody who is unimportant or irrelevant.

In a martensitic manner.

In a state of excitement, agitated activity, or motion. / Bubbling.

The view, originating in the Middle Ages, that history is a linear succession of transfers of an imperium that invests supreme power in a single ruler.