One Word Substitution

Hippopotamus is the odd one out because it's an amphibious mammal that lives primarily in water. Bull, Rhinoceros, and Unicorn are all land-dwelling mammals (unicorn being mythical). The hippo's aquatic lifestyle makes it distinct.

Three words derive from Latin 'caput' (head): capital (head/money), chattel (property), and cattle (property/wealth). Chateau comes from Latin 'castellum' (castle), not from 'caput'. This question tests etymological knowledge and word origins.

Omphaloskepsis is the actual word for navel-contemplation as a meditation practice, derived from Greek 'omphalos' (navel) + 'skepsis' (contemplation). The other options are unrelated: melancholy (sadness), deliquesce (dissolve), rankle (irritate).

Dotage specifically refers to the period of life when an elderly person becomes weak or foolish in mind. Imbecility means stupidity, senility is general decline in old age, and superannuation is retirement due to age. Dotage best captures the 'behaving like a fool' aspect.

Correct Answer: Viaticum

Biopsy and surgery are conducted on living beings. Postpartum relates with birth.

'Auto' means self and 'bio' means life - story of one's own life.

We can easily link up the word with 'transport'.

Drought involves lack of rainfall or water. Both 'cultivate' and 'germinate' depend on water or 'irrigate'.

'Ex' means out; 'tempore' means time. This is a speech where no time is allowed for preparation.

'Hom' (same) + 'phon' (sound)

Potable is fit to drink; 'audible' is within hearing; and 'eligible' is fit to be chosen.

All other words also involve some sort of knife, but not a gun.

All 'ologies' are studies. But 'phil' means love (love of studies), 'hor' means time (study of timings); and 'geo' means 'earth' (study of structure of earth).

All, except 2, are matters of attitude or bearing.