surrogate mother

noun 0.832

surrogacy

noun 0.786

surrogate father

noun 0.783

substitute

noun 0.589

stand-in

noun 0.560

foster mother

noun 0.558

succedaneum

noun 0.544

understudy

noun 0.542

surfactant

noun 0.537

survivor

noun 0.536

surd

noun 0.535

surfer

noun 0.534

nanny

noun 0.528

foster

noun 0.528

co-parent

noun 0.524

supplanter

noun 0.523

foster parent

noun 0.522

subaltern

noun 0.521

successor

noun 0.519

supersede

noun 0.519

proxy

noun 0.517

ersatz

noun 0.516

deputy

noun 0.516

go-between

noun 0.515

simulant

noun 0.514

subdelegate

noun 0.514

substitutable

noun 0.513

surveyor

noun 0.511

servant

noun 0.511

servent

noun 0.510

supervisor

noun 0.510

guardian

noun 0.510

surgeon

noun 0.508

midwife

noun 0.508

au pair

noun 0.508

alternate

noun 0.507

supposer

noun 0.507

usurper

noun 0.506

replacement

noun 0.506

supernumerary

noun 0.506

caregiver

noun 0.505

wet nurse

noun 0.502

surplus

noun 0.502

doula

noun 0.501

spare

noun 0.501

usherette

noun 0.500