We don't have synonyms for kilogrammes yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are kilogramme and kilograms.
(n) :
(British spelling) Alternative spelling of kilogram. [In the International System of Units, the base unit of mass; conceived of as the mass of one litre of water, but now defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10⁻³⁴ when expressed in units of kg⋅m²⋅s⁻¹. Symbol: kg]
(n) :
(British spelling) Alternative spelling of kilogram. [In the International System of Units, the base unit of mass; conceived of as the mass of one litre of water, but now defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10⁻³⁴ when expressed in units of kg⋅m²⋅s⁻¹. Symbol: kg]