Not usually. There are two major exceptions though:
--If the word has been adopted into the English language, then yes. Make sure you check an English dictionary to see if the word is there.
--If you are playing a non-English version of Scrabble, then they definitely are, and English words might be off-limits.
JO is an acceptable scrabble word. Searching the internet many sites have all the acceptable words for a game of scrabble and JO is repeated on 90% of these websites as being correct.
YES, XI is acceptable (it's a Greek letter). [HINT: All of the letters of the Greek alphabet are acceptable words in Scrabble.]
URL is not an acceptable Scrabble word. Merriam-Webster's Official Scrabble Players Dictionary is the official scrabble dictionary. URL is not included in the official dictionary as an acceptable word. Abbreviations are not acceptable words unless the letters also form a word that is a part of speech.
No. Fo is not an acceptable Scrabble word.
no you cannot use foreign words or proper nouns in scrabble unless at the beginning everyone agrees that you can use foreign words and names. But the names can only be of someone widely known.
No. You are allowed to use only the words for the language version of Scrabble you are playing. However, if two people want to play a game of Scrabble and allow foreign words, they can make up whatever supplemental rules they like. There are no universal Scrabble police to stop you.
Words that are always capitalized are not acceptable words in Scrabble.
JO is an acceptable scrabble word. Searching the internet many sites have all the acceptable words for a game of scrabble and JO is repeated on 90% of these websites as being correct.
YES, XI is acceptable (it's a Greek letter). [HINT: All of the letters of the Greek alphabet are acceptable words in Scrabble.]
See related links for a list of official Scrabble 2-letter words.
URL is not an acceptable Scrabble word. Merriam-Webster's Official Scrabble Players Dictionary is the official scrabble dictionary. URL is not included in the official dictionary as an acceptable word. Abbreviations are not acceptable words unless the letters also form a word that is a part of speech.
No. Excelsis is not an acceptable Scrabble word.
No. Viz is not an acceptable Scrabble word.
No. Cie is not an acceptable Scrabble word.
Abbreviations are not acceptable in Scrabble.
Yes, conjunctions are words, and are hence acceptable plays in Scrabble (so long as these words appear in the Official Scrabble Players Dictionary, 4th Edition).
Yes. Any word that meets the Scrabble rules is allowed (e.g. allowed and aloud both are acceptable Scrabble words).