Logos is the Greek word for "speech" or "word,” but John uses this term to refer specifically to God's word personified as Jesus. No other Gospel writer uses logos like this. However, since Heraclitus first used the term around 500 BC, ancient Greek philosophers used logos to mean wisdom in general, particularly pertaining to divine order and reasoning.
Many Bible translations capitalize "word" when referring to Jesus. Similarly, pronouns ("he" or "his") referring to God or Jesus are typically capitalized throughout Scripture. However, there was no concept of capitalization in the original languages of the Bible. Over time, church tradition has capitalized any titles or pronouns referring to God, but this practice isn't directly biblical.