Clochard is a French word meaning a beggar or a vagrant. It comes from the French verb clocher1, meaning 'to limp', which comes in turn from the Latin clopus, meaning 'lame'. In English it is pronounced 'kloh-sherd'.
This word is relatively new to the English language. The OED records its first English usage in Hemingway's book For Whom the Bell Tolls, published in 1940. It still makes appearances in the writings of those who cannot resist a good thesaurus, but is far from being in common usage.
One context in which you might see the word clochard used in English is in the field of photography. The French humanist school of photography frequently focused on the clochard as a particularly human figure. They remain an 'artsy' subject today, and the French is often used when talking about these photos. (Here's an external link for you2).
If you are in France, a clochard is generally a homeless person, with an overtone of wino. A female would be a clocharde.
1. An alternate etymology! Mouesh says re Clochard: Most cities of France used to have fortifications and come the night, the church bell (cloche in French) would tell the poor, the bums and the workers who could not afford to live in town to vacate the premises of the city. Many were drunk, tired, or injured and did not walk straight when leaving. From this and the fact that the word clocher (Latin verb claudicare) which means to limp, came the denomination "clochard".
2. If you'd prefer to copy and paste the link, here it is: http://www.paris-pittoresque.com/gravures/metiers/20.htm