geminate

adj

1. (not-comparable)Forming a pair.

   “Near-synonyms: paired, doubled, twinned”

2. (not-comparable)Pronounced longer and considered as being doubled.

   “For example, Martin (2007) notes that compounds in several languages (including English and Turkish) violate the general phonological principles in the language (e.g., English only allows geminate consonants in compounds).”

verb

1. To arrange in pairs.
2. To occur in pairs.

noun

1. A doubled or repeated letter or speech sound.

   “The attested forms show variation in the unstressed vowels (Srd. lèppere, lèpporo, lèppore, léppuri etc.) but agree on the labial geminate. We can thus reconstruct *leppVr-.”