Voiced alveolar tap or flap in the context of "Peter Ladefoged"

In phonetics, rhotic consonants, or "R-like" sounds, are liquid consonants that are traditionally represented orthographically by symbols derived from the Greek letter rho (Ρ and ρ), including ⟨R⟩, ⟨r⟩ in the Latin script and ⟨Р⟩, ⟨p⟩ in the Cyrillic script. They are transcribed in the International Phonetic Alphabet by upper- or lower-case variants of Roman ⟨R⟩, ⟨r⟩: ⟨r⟩, ⟨ɾ⟩, ⟨ɹ⟩, ⟨ɻ⟩, ⟨ʀ⟩, ⟨ʁ⟩, ⟨ɽ⟩, and ⟨ɺ⟩. Transcriptions for vocalic or semivocalic realisations of underlying rhotics include the ⟨ə̯⟩ and ⟨ɐ̯⟩.

This class of sounds is difficult to characterise phonetically; from a phonetic standpoint, there is no single articulatory correlate (manner or place) common to rhotic consonants. Rhotics have instead been found to carry out similar phonological functions or to have certain similar phonological features across different languages.

In linguistics, lenition is a sound change that alters consonants, making them "weaker" in some way. The word lenition means 'softening' or 'weakening' (from Latin lēnis 'weak'). Lenition can happen both synchronically (within a language at a particular point in time) and diachronically (as a language changes over time). Lenition can involve such changes as voicing a voiceless consonant, causing a consonant to relax occlusion, to lose its place of articulation (a phenomenon called debuccalization, which turns a consonant into a glottal consonant like [h] or [ʔ]), or even causing a consonant to disappear entirely.

An example of synchronic lenition is found in most varieties of American English, in the form of tapping: the /t/ of a word like wait [weɪt] is pronounced as the more sonorous [ɾ] in the related form waiting [ˈweɪɾɪŋ]. Some varieties of Spanish show debuccalization of /s/ to [h] at the end of a syllable, so that a word like estamos "we are" is pronounced [ehˈtamoh]. An example of diachronic lenition can be found in the Romance languages, where the /t/ of Latin patrem ("father", accusative) has become /d/ in Italian (an irregular change; compare saeta "silk" > seta) and Spanish padre (the latter weakened synchronically /d/ → [ð̞]), while in Catalan pare, French père and Portuguese pai historical /t/ has disappeared completely.

Resh /rɛʃ/ is the twentieth letter of the Semitic abjads, including Phoenician rēš 𐤓, Hebrew rēš ר‎, Aramaic rēš 𐡓‎, Syriac rēš ܪ, and Arabic rāʾ ر‎. It is related to the Ancient North Arabian 𐪇‎‎, South Arabian 𐩧, and Ge'ez ረ. Its sound value is one of a number of rhotic consonants: usually [r] or [ɾ], but also [ʁ] or [ʀ] in Hebrew and some North Mesopotamian Arabic dialects.

In most Semitic alphabets, the letter resh (and its equivalents) is visually quite similar to the letter dalet (and its equivalents). In the Syriac alphabet, the letters became so similar that now they are only distinguished by dots; resh has a dot above it, and the otherwise identical dalet has a dot below. In the Arabic alphabet, rāʼ has a longer tail than dāl. In the Aramaic and Hebrew square alphabet, resh is a rounded single stroke while dalet is two strokes that meet at right angles.