Greenhorn

Despite its adoption in America to describe a young, inexperienced novice, this is an old English word dating from around 1460 when it was first used to describe a young, horned animal. Green of course is used in its familiar sense of unripe or inexperienced. Its first use to describe an inexperienced novice dates from around 1650 when it specifically referred to soldiery. Thereafter, its meaning was extended to any inexperienced novice in any profession.