What does this mean?

I am a fairly new knitter, and am trying to make a baby afghan for my friend. The pattern calls for “double knitting weight yarn” I could not find any at the store, and I have never heard of this. Where can I find it, or what does it mean. I got some regular baby yarn, and it does not say anything on this particular yarn about weight. Help!!

Thanks.

Becky

it is more commonly known as DK weight i think. There is a chart here that shows the differences in weights and their gauges.

The yarn I got says “sport d.k.” on it, so I guess I will go ahead and use it! Thanks for your help!!