From BiblePortal Wikipedia

King James Dictionary [1]

M`Ar, L marceo.

1. To injure by cutting off a part, or by wounding and making defective as, to mar a tree by incision.

I pray you, mar no more trees by writing songs in their barks.

Neither shalt thou mar the corners of thy beard.  Leviticus 19

2. To injure to hurt to impair the strength or purity of.

When brewers mar their malt with water.

3. To injure to diminish to interrupt.

But mirth is marred, and the good cheer is lost.

4. To injure to deform to disfigure.

Ire, envy and despair

Marr'd all his borrow'd visage.

His visage was so marred more than any man.  Isaiah 52

Moral evil alone mars the intellectual works of God.

This word is not obsolete in America.

Webster's Dictionary [2]

(1): ( n.) A mark or blemish made by bruising, scratching, or the like; a disfigurement.

(2): ( n.) A small lake. See Mere.

(3): ( v.) To make defective; to do injury to, esp. by cutting off or defacing a part; to impair; to disfigure; to deface.

(4): ( v.) To spoil; to ruin.

International Standard Bible Encyclopedia [3]

mar  : "To mar" means "to destroy," "to disfigure," "to damage."   Job 30:13 , "They mar my path" (the Revised Version margin "they break up");  Nahum 2:2 , "and destroyed their vine" (the King James Version "and marred their vine"); compare  Leviticus 19:27;  2 Kings 3:19;  Isaiah 52:14;  Jeremiah 13:9 .

The Nuttall Encyclopedia [4]

A district in S. Aberdeenshire, between the Don and the Dee, has given a title to many earls; one was regent of Scotland in 1572, another, nicknamed "Bobbing Joan," led the Jacobite rising of 1715; on the death without issue of the earl in 1866 the question of succession was at issue; the Committee of Privileges granted it to his cousin, the Earl of Kellie, thereafter Mar and Kellie, and a Bill in Parliament awarding it to his nephew, who is thus Earl of Mar.