From AmtWiki

In heraldry, a motto is often depicted in an achievement of arms, typically on a scroll below the shield, or else above the crest as in Scots heraldry. Although very unusual and perhaps outside regular heraldic practice, there are some examples of the particular appearance of the motto scroll and letters thereon being blazoned on the shield proper.

A motto (from Italian) is a phrase or a short list of words meant formally to describe the general motivation or intention of an entity, social group, or organization. Many countries, cities, universities, and other institutions have mottos, as do families with coats of arms. A motto may be in any language. Latin and to a lesser degree French are disproportionately frequent, because each was the principal international language for a considerable period. The local language is usual in the mottos of governments.

A canting motto is one that contains word play. For example, the motto of the Earl of Onslow is Festina lente, punningly interpreting on-slow (literally "make haste slowly").