A gyre is another name for a swirling vortex. Ocean gyres are large swirling bodies of water that are often on the scale of a whole ocean basin or 1000 s of kilometers across (hundreds to thousands of miles across).
Lean meats are meats with a relatively low fat content. Skinless chicken and turkey and red meat, such as pork chops, with the fat trimmed off are examples of lean meat.
Lean(verb) of a character which prevents the compositor from earning the usual wages; -- opposed to fat; as, lean copy, matter, or type. Lean(noun) that part of flesh which consist principally of muscle without the fat. Lean(noun) unremunerative copy or work.