I am relatively a new chess player and been improving my strength in the opening for a while and would like to know which opening is the most defensive. 1.e5 seems a little too aggressive.
This is a subjective question, so I'll give a subjective answer. In my opinion, the Hippopotamus Defense is the most defensive opening. Here's a typical Hippopotamus structure -
[FEN "r2qk2r/pbpnnpbp/1p1pp1p1/8/2PPP3/2N1BN2/PP2BPPP/R2Q1RK1 w kq - 0 9"]
Black doesn't even move a pawn to the 4th rank! All of Black's minor pieces are developed on the second rank and Black keeps his pawns on the third rank. Essentially, Black plays a waiting game for a while, and tries to provoke White into doing something concrete and then Black reacts accordingly.
P.S. Since you're a beginner, I would advise NOT to use this opening. Yes, it is the most defensive opening, but if you're afraid of playing 1...e5 then you ought to first correct that instead of trying to play something else! Even with 1...e5, Black can reach defensive setups.
One chess opening you can use is the Hedgehog formation, it is very defensive if you are playing black. Black exchanges a pawn on c5 for a white pawn on d4 and then places his pawns on a6, b6 and e6. The bishops are placed on b7 and e7, then the knights are placed on d7 and f6, the queen is on c7 and the rooks on c8 and e8. This position is cramped, however it has great defensive capabilities.
[FEN "2r1r1k1/1bqnbppp/pp1ppn2/8/8/8/8/8 w - - 0 1"]
If you are looking defensive openings for black I would recommend Caro Kann Against 1.e4
[FEN ""] 1. e4 c6 2. d4 d5
Slav defense against 1.d4
[FEN ""] 1. d4 d5 2. c4 c6
Be careful though, Because Caro Kann isn't exactly an opening for beginners and Some variations of Slav can lead to position requiring precise Tactical play.
In a standard French exchange defense the goal is to reach the endgame as soon as possible. It typically leaves the king's rook file open with pawns on b2, b3, and c2 for white and vice versa for black and a castled king-side. Only the rooks and queens are left in play. Besides all the exchanges it leads to a long and tedious (very passive)endgame. In my studies I find the Sicilian dragon in response to the English fianchetto (copy cat essentially) leads to a waiting game until the first decides to make an advancing move.
Ultimately however it all relies on the player. Garry Kasparov for example loves to attack and with devastating effect. However one can choose to play passive and slowly take their opponent down. The best advice would be to experiment with all the defenses mentioned and see which you prefer or find some of your own. Best of luck with your search!
Looking back to my earlier days I would recommend Petrov's Defence. 1) e4 e5 2) Nf3 Nf6 which, with a bit of luck, will turn into the safe, boring 4 Knights.
I know you think e5 is too aggressive. It isn't. Other moves are too passive and according to Chessbase you will lose more games with other replies. You will find defence much easier if you haven't already given away the center.
You will need to have an answer to the King's Gambit. Either an early d4 or Fischer's Defense were what I used in my early days.
Nowadays I play either the French or the Lion (a variation of Philidor's which delays e5 until move 3 or later) but both of these require more book learning and can have some very aggressive variations indeed.