A small glass bottle which has been or can be sealed hermetically by application of flame to a narrow opening at the top. Note: aAn ampule usually has a narrow constriction near the top which can be scored and easily broken to open the ampule. Once opened, they cannot be hermetically re-sealed; thus the quantity contained is usually that which is to be used at once or within a short time. The contents are often sealed under vacuum to retard degradation by air.
