Jackrabbit is back.

The suspension of cornerback Janoris Jenkins lasted one game, as on Tuesday, he was reinstated by the Giants.

Jenkins was suspended indefinitely last week after he failed to return following the bye week, missing a Monday practice. Two other players, cornerback Eli Apple and running back Paul Perkins, also missed that practice, but alerted the team about their travel difficulties and only were hit with a fine. Jenkins failed to notify the Giants of his whereabouts and thus was suspended by Ben McAdoo. Jenkins did not play in the 51-17 loss to the Rams and lost $758,823 — one game check off his 2017 base salary of $12.9 million.

Without Jenkins — the team’s top cornerback — the defensive backfield was in shambles, as Jared Goff shredded the Giants for a career-high four touchdown passes, needing only 22 passes to amass 311 yards.

Jenkins was the second cornerback suspended by McAdoo in a three-week period, following Dominique Rodgers-Cromartie’s one-week banishment after four violations of team rules, most notably walking out of the team facility on a workday.

The suspension and multiple injuries left the Giants desperate for bodies against the Rams, and they showed just how desperate Tuesday by parting ways with three players who suited up for that game. They waived defensive end Jordan Williams and defensive back Tim Scott — both signed last week off the practice squad — and put linebacker Nigel Harris on injured reserve with an injury to his ribs.

The Giants reacquired linebacker Deontae Skinner, who was with the team earlier this season and most recently on the Raiders practice squad.

LB B.J. Goodson did not play against the Rams because of a high ankle sprain and he does not sound optimistic about returning this weekend to face the 49ers. “This is like really, really nagging,’’ Goodson told The Post. “I’ve had injuries where I just had to be down and I couldn’t move in a certain area. This is like very, very frustrating.’’

In dire need of healthy bodies at linebacker, the Giants re-signed Kelvin Sheppard, who played in every game for them last season. Sheppard, a seven-year veteran, started 11 games at middle linebacker in 2016. He was with the Bears this summer and cut prior to the season. Sheppard, 29, has played in 93 games in the NFL, starting 56 games for the Bills, Colts, Dolphins and Giants.

If misery indeed loves company, the Giants and 49ers will get along just fine this weekend. The 49ers are so banged up they do not have enough healthy players to fill out a 46-man game-day roster. “We’re going to have to sign some guys,’’ coach Kyle Shanahan said Tuesday. “We plan on signing some guys here in the next couple days. I know they’re working on it right now into tomorrow. So, we’re going to have to figure that out before Wednesday.” Shanahan said QB C.J. Beathard is “sore’’ coming out of the 20-10 loss to the Cardinals but remains the starting quarterback, leaving Jimmy Garoppolo, newly acquired in a trade with the Patriots, the backup.

Remember that atrocious 52-yard touchdown given up by the Giants to the Rams on third-and-33? It doesn’t happen often. The last team to convert a third-and-33 or greater was the Bengals (third-and-34) on Sept. 20, 2009, at Green Bay.