Welsh Etymology Adapted from English tangent + -iad. Noun tangiad m (plural tangiadau) (mathematics, differential geometry) tangent Synonym: (obsolete) cyffyrddlin Related terms trigonometreg (“trigonometry”) sin (“sine”) cosin (“cosine”) References R. J. Thomas, G. A. Bevan, P. J. Donovan, A. Hawke et al., editors (1950–present), “tangiad”, in Geiriadur Prifysgol Cymru Online (in Welsh), University of Wales Centre for Advanced Welsh & Celtic StudiesWikiwand - on Seamless Wikipedia browsing. On steroids.