Designating a chromatid or a chromosome that lacks a centromere (King et al. 2006). This condition may arise in an inversion heterozygote as a result of crossing over between a normal and an inverted segment that does not include the centromere (Schlindwein 2006). A chromosome, or chromosome fragment, that lacks a centromere (Hoy 2003). See ‘centromere’, ‘dicentric’, ‘monocentric’, ‘holokinetic’, ‘monokinetic’.