Definition of OTT in English:

1980s: short for over the top.

• top from Old English:

  Found in Old English, a child's toy, related to tip; came from Old Norse in Middle English. The expression to go over the top originated in the First World War, when it described troops in the trenches charging over the parapets to attack the enemy. It gradually developed the meaning ‘to do something to an excessive or exaggerated degree’, possibly in reference to the huge numbers of soldiers who died in the conflict. Soon people were shortening it to simply over the top, and since the early 1980s it has been reduced even further to the abbreviation OTT, particularly when referring to acting. See also sleep