Boho is not short for bohemian as there is no “O” in the word after the “H”, but it is part of the meaning.
Bo = Bohemian / Ho = Hobo (see meanings at the bottom)
Mary-Kate & Ashley, the Olsen sisters are icons of this style, as it was coined after them. The word is often now used for to describe just a Bohemian/gypsy look but it’s not the correct meaning.
Below are a couple of photos that typifies the look, as you can see it’s more that just a dreamy hippy look (taken from the Bohemian / unconventional time of the 70’s). The look has a slight “Bag Lady” feel (the Hobo part of the look), while still remaining very designer as we would expect from the Olsen twins…!
From the Concise Oxford Dictionary:
Bohemian: 1. (Native or inhabitant) of Bohemia; Czech. Socially unconventional (person); person, esp. artist or writer, of free-and-easy habits, manners, and sometimes morals.
Hobo: Wandering workman or tramp
Note: How do I know all about this? I worked under Trish (at DesignWorks) as the Australian designer for the Mary-Kate& Ashley label…!