constitution/ custom/ guise/ habitude/ law/ manner/ rule/ usage
adversarial/ adverse/ devilish/ fiendish/ hostile/ oppugnant
animosity/ antagonism/ beef/ enmity/ hostility/ ill will/ inimicality
difficult/ hard/ inconvenient/ intractable/ laborious/ operose/ trying
accusation/ challenge/ charge/ claim/ contention/ demand/ indictment/ lawsuit/ pretention/ pronouncement/ proposition/ theory
betrayal/ deceit/ deception/ delusion/ double cross/ indirection/ wile
double dealing/ infidelity/ knavishness/ quackery/ treachery/ unfaithfulness/ wilfulness
bureau/ cahier/ muster/ notebook/ notepad/ office/ portfolio/ record/ register
grind/ hagride/ harass/ irk/ molest/ plague/ tease/ torment/ vex
difficulty/ dilemma/ hardness/ intricacy/ labour/ perplexity/ problem/ trouble
abstract/ abstruse/ critical/ deep/ delicate/ difficult/ fine/ minute/ nice/ scholastic/ subtle/ thin