a cardinal number represented by 1 followed by 36 zeros, or (esp in older British usage) by 1 followed by 66 zeros
adjective
2.
amounting to one undecillion in number
Derived forms
undecillionth
adjective or noun
Word origin
[1930–35; ‹ L undec(im) eleven (ūn(us) one + -decim, comb. form of decemten) + -illion, as in million]This word is first recorded in the period 1930–35. Other words that entered Englishat around the same time include: cloverleaf, old school tie, preset, saddle stitch, uncertainty principle