I think the female barrel is on the Arduino board and the male plug is with the wire to the power adapter.
The pin in the middle is ignored when naming it female or male. And some call it "Jack".
No. The female barrel jack has a male center plug. It is technically BI-SEXUAL...
We are all saying the SAME thing in DIFFERENT WAYS.
The UNO JACK is a FEMALE JACK (that means it has a HOLE !) with a MALE PIN in the center of the HOLE.
The plug on the power supply linked by the OP is the RIGHT SEX (it is a cylinder with a HOLE in the center). As long as the dimensions of the hole and the OD are correct , it should work because it is CENTER POSITIVE (ANOTHER variable in the equation. Not ALL such plugs are CENTER POSITIVE).
The UNO requires CENTER POSITIVE "plug" (called a "plug" because it looks like a SHAFT which is designed to go in a HOLE ) (make a circle by touching your thumb and forefinger and stick your other forefinger in and out of the hole....The hand with the hole is the JACK. The forefinger of the other hand is the PLUG. (I can't believe we have to spell this out. The OP was correct in his first post. That power supply will work if the dimensions are correct)
Sparkfun says:
"The gender of the pins inside the connector is what signifies the gender of the connector as a whole..."
Well FXCK SPARKFUN then because we've been calling the connector on the UNO a "BARREL-JACK" since day one because it receives the shaft shaped plug on the end of the AC/DC wall-wart adaptor DESPITE the fact that the wallwart plug has a hole in the center and the barreljack has a pin in the center.
If OldSteve and I were working together and he had the MOLEX plug shown in Reply#11, and he was looking for the mate, he would say to me:
"Have you seen the Male plug with Female pins that mates with this plug ? (I wouldn't call that a "jack" because "jack" implies a hole recessed into a flat or rounded surface.) Most products sold by RadioShack that come with an AC/DC wallwart adaptor have a plastic housing or body with a flat surface with a hole recessed into it with a pin in the center. It's called a "jack" because it is a hole recessed into a flat surface ( the UNO barreljack is ACTUALLY an exception to the rule because MOST consumer products follow the RadioShack model of hole recessed into a flat surface, even though if you remove the entire housing you will find the exact same PC-MOUNT BARRELJACK underneath the housing and the housing has a round piece around the hole to structurally reinforce the plastic
where the hole is so the barreljack fits flush against the housing which conceals the outer rim of the barreljack revealing only the hole. When you remove the product from the box you scan all four sides at the bottom surface looking for the hole which coceals the body of the PC-MOUNT barreljack, just like the one on the UNO.
raschemmel:
(I can't believe we have to spell this out. The OP was correct in his first post. That power supply will work if the dimensions are correct)
FNARR.
Quite but a bigger SHAFT will convey more OOMFH.
Dolphins carry their bits shrouded..
Perhaps the arduino connector could be called a dolphin coupler
OK iv had a few.
The bottom line is don't depend on descriptions using words plug, jack, male, female.
It must be detailed like: pin in the middle inside barrel socket or barrel with conducter on outside with socket in the middle.
Best would be to look at what you have and buy the other one, regardless of what they call it. Pictures are good if they depict the actual product being purchased. IE no disclaimers about 'picture may not represent the product'.
My take on this is that barrel jacks are a poor design at best, and the bewildering variety of sizes
and lengths and polarities is indicative of a sorry state of affairs. But there isn't much alternative
alas.
Lets hope someone somewhere is designing a better kind of connector, with positive locking, pin
spacing to identify voltage class (5, 9, 12 or 24), and colour coded for power or something like that.
It shouldn't be rocket science to come up with standardized connectors for DC power that are robust,
logical and can't be connected wrongly...
-- Don't get me started on RCA audio connectors...
Till now 
