-a-

From of a (as in half-a-crown) or of (as in jack-a-napes from Middle English Jak of Naples). Some terms have fully incorporated the use, as ragamuffin and jackanape(s); others arise from mistaken assimilation to the form, as all-a-gog and cock-a-leekie.

-a-

1. Connective infix used in forming compounds, often no longer carrying a distinct meaning.

• o'

From earlier a (attested by the 14th c.), as a contraction of and and its various Middle English forms.

-a-

1. And
   • 1746, Exmoor Scolding 3rd ed., 81

     Chem a laced well-a-fine aread

• an', n'

From French à (“various prepositions”) and related prepositions in other Romance languages. Also from related misunderstandings, as all-a-mort from French à la morte.

• à, -à-

-a-

1. Connective infix encountered in loanwords and phrases, generally no longer carrying a distinct meaning.

-a-

1. (chemistry) Replacing carbon especially in a ring.

The vowel of rat

-a-

1. (pharmacology) A monoclonal antibody derived from a rat.

• -mab is the base suffix common to all monoclonal antibodies

• USP Dictionary of USAN and International Drug Names, U.S. Pharmacopeia, 2000

-a-

1. Forms the past perfect tense in verbs.

This contrasts with the simple past, -na-/-da-, which does not imply completion.

-a-

1. A suffix-initial vowel (or linking vowel) inserted interconsonantally between the word stem and the suffix, to ease pronunciation, without contributing to the meaning.

   ‎fiatal (“young”) + ‎-a- + -bb → ‎fiatalabb (“younger”)

• -á-
• -e-
• -o-
• -ö-