synonyms - What are the differences of meaning between device, gadget, gimmick, and gizmo?

Further to my earlier question about the words off-the-shelf used in Time Magazine’s feature story titled “The Best 50 Inventions of the Year” (from the Nov. 11th 2010 issue), I found the following sentence in the same article:

One analyst says the iPad is the fastest selling non-phone gizmo in consumer electronics history.

I understand there is some difference of meaning between device and gizmo / gadget and gimmick as a group. Are there great difference of meaning and usage between the words gizmo, gadget, and gimmick?

Answer

A gizmo is

a gadget, especially one whose name the speaker cannot recall.

Synonyms might be "thingamajig" or "whatsit" (colloquially).

A gadget is

a small mechanical device or tool, especially one that is ingenious or novel.

Smallness is one of the defining characteristics, so a new type of earth-moving equipment is not likely to be called a gadget, however ingenious or novel it may be, but a pen that doubles as a voice recorder certainly would be.

A gimmick is merely a trick, usually used to attract attention or publicity. A gimmick does not have to be a mechanical device. This is the "black sheep" in your list.

Device is a bit broader:

1 a thing made or adapted for a particular purpose, esp. a mechanical or electronic contrivance : a measuring device. • an explosive contrivance; a bomb : an incendiary device. • archaic the design or look of something : works of strange device.

2 a plan, scheme, or trick with a particular aim : "writing a public letter is a traditional device for signaling dissent." • a turn of phrase intended to produce a particular effect in speech or a literary work : a rhetorical device.

3 a drawing or design : the decorative device on the invitations. • an emblematic or heraldic design : their shields bear the device of the Blazing Sun.

(Above definition taken from Webster's.)