Can refer to a small spike or secondary spike, but is also the most basic floral unit in the grass family.  A whole grass spikelet generally consists of 2 glumes (an upper glume and a lower glume) situated below one to many grass flowers/florets that alternate along the rachilla (the main spikelet stem/axis).  Depending on a given species, spikelet parts can be missing and florets can be unisexual.