"hadst all oneself" can be defined as having complete control or possession over something. There are multiple synonyms that can be used to convey this meaning, such as being the sole owner or having sole authority. Other synonyms include having exclusive possession or complete autonomy. Additionally, phrases like having complete domination or total mastery over something can also be used as synonyms for "hadst all oneself". Essentially, any term that expresses complete possession or control can be used to convey a similar meaning to "hadst all oneself". These synonyms can provide writers and speakers with a range of options to convey their intended message more effectively.