TS: Study ETYMOLOGY.
earth
O.E. eorðe "ground, soil, dry land," also used (along with
middangeard) for "the (material) world" (as opposed to the heavens
or the underworld), from P.Gmc. *ertho (cf. O.N. jörð, M.Du. eerde,
O.H.G. erda, Goth. airþa), from PIE base *er-. The earth considered
as a planet was so called from c.1400. Earthy in the fig. sense of
"coarse, unrefined" is from 1594. Earthworm first attested 1591.
Earthwork is from 1633. Earthlight apparently coined 1833 by
British astronomer John Herschel.
Source:
http://www.etymonline.com/index.php?search=earth&searchmode=none
water (n.1)
O.E. wæter, from P.Gmc. *watar (cf. O.S. watar, O.Fris. wetir, Du.
water, O.H.G. wazzar, Ger. Wasser, O.N. vatn, Goth. wato "water"),
from PIE *wodor/*wedor/*uder-, from root *wed- (cf. Hittite watar,
Skt. udnah, Gk. hydor, O.C.S., Rus. voda, Lith. vanduo, O.Prus.
wundan, Gael. uisge "water;" L. unda "wave"). Linguists believe PIE
had two root words for water: *ap- and *wed-. The first (preserved
in Skt. apah) was "animate," referring to water as a living force;
the latter referred to it as an inanimate substance. The same was
probably true of fire (n.). To keep (one's) head above water in the
fig. sense is recorded from 1742. Water cooler is recorded from
1846; water polo from 1884; water torture from 1928. First record
of water-closet is from 1755. Water-ice as a confection is from
1818. Watering-place is 1440, of animals, 1757, of persons.
Water-lily first attested 1549. Waterfront is attested from
1856.
