Oxford English Dictionary

Consonant: 1. An alphabetic or phonetic element other than a vowel; an elementary sound of speech which in the formation of a syllable is combined with a vowel. Applied both to the sounds and to the letters (the latter being the historically prior use).

Vowel:   1.  A sound produced by the vibrations of the vocal cords; a letter or character representing such a sound (as a, e, i, etc.).
  ‘A vowel may be defined as voice (voiced breath) modified by some definite configuration of the super-glottal passages, but without audible friction (which would make it into a consonant)’ (Sweet Primer of Phonetics, ed. 2, §32).

 Diphthong:   A union of two vowels pronounced in one syllable; the combination of a sonantal with a consonantal vowel.
  The latter is usually one of the two vowels i and u, the extremes of the vowel scale, which pass into the consonants y, w. When these sounds, called by Melville Bell glides, follow the sonantal vowel, the combination is called a ‘falling diphthong’, as in out, how, boil, boy; when they precede, the combination is a ‘rising diphthong’, as in It. uovo, piano. It is common in the latter case to consider the first element as the consonant w or y.

Pronunciation of the word Kestrel:

Philology: Love of learning and literature; the branch of knowledge that deals with the historical, linguistic, interpretative, and critical aspects of literature; literary or classical scholarship.

The etymology of “crow”:

[OE. cráwe f., corresp. to OS. krâia, MLG. krâge, krâe, krâ, LG. kraie, kreie, MDu. kraeye, Du. kraai, OHG. chrâwa, chrâja, chrâ, crâwa, crâ, MHG. kræe, krâwe, krâ, Ger. krähe; a WG. deriv. of the vb. crâwan, crâian to CROW, q.v.]