How get the original index after use Dataframe.iloc(bool)

df= pd.read_csv("3.csv")
df=df.loc((df['column 1'] != "abc") & df['column 2'] == "def" ) # return a series by using boolean find

assume df will got 10 rows so now df will be maybe selected 5 from orignal df. Then example data maybe

#example value as table format
<> column 1 column 2 column3
0  abc      def       z 
1  abc      def       s  #original maybe 3
2  abc      def       q  #ori 7
3  abc      def       2  #8
4  abc      def       l  #9

Are there any way to maintain the original index value? Because I want to update the orignal dataframe with the selected value. Tried something like df.index but it is the latest index