Et-was = some-what, some-thing

Nimm irgendetwas (take anything, just take something); das ist etwas schwierig (that is somewhat difficult, a little difficult)

The older language also had et-wer (somebody), but this has died out (apart from dialectal usage).

Et-wa = originally "somewhere (about)" = circa, approximately

Das sind etwa 2 km von hier (that should be about 1.5 miles from here). Vor etwa zwanzig Minuten, würde ich sagen (about 20 Minutes ago, I'd say). 

There is also etliche (= many, originally "some, any").