arbitrary
random
arbitrary
The word random has no meaning in this question.
"Random" is a word which has the meaning haphazard without aim.
choice
no known pattern
The beginning of a word is called the prefix. It is a group of letters added to the beginning of a root word to change its meaning.
http://thesaurus.reference.com/browse/beginning
What is a word that starts with X meaning nice or playful
A prefix.
A prefix is a syllable that is added to the beginning of a word to change its meaning or create a new word.
authority