Proclive

• (a.) Having a tendency by nature; prone; proclivous.
Found on http://thinkexist.com/dictionary/meaning/proclive/

Proclive

Pro·clive' adjective [ Latin proclivis sloping, inclined; pro forward + clivus hill: confer French proclive . See Declivity , and confer Proclivous .] Having a tendency by nature; prone; proclivous. [ R.] Mrs. Browning.
Found on http://www.encyclo.co.uk/webster/P/166
No exact match found