Hello Linear, amico ,amica , amici all mean "friend" ,but: amico is the masculine , male friend amica is feminine , female friend amici is masculine plural ( male or both female and males "mixed"friends) amiche refers only to feminine plural ( female friends) Since you are a beginner it is good for you to know that a masculine noun in Italian often ends in (O) and its female counterpart in (A), their masculine plural in (I) and their feminine plural in ( E) as in 'la donna' and 'le donne' An example: ragazzo (boy) ragazza ( girl) ragazzi ( children, guys, boys and girls *plural* ) ragazze ( girls in the plural) As for "libro "( book) it is a masculine noun ,but it doesn't have a feminine ,there is no masculine book and another feminine book ;) Notice that not all nouns have the masculine and feminine versions. un libro "Libra" doesn't exist in Italian. un libro i libri ( its plural, which is a masculine plural)