in Gaelic. The next group is even more obvious as "two participants whith some form of feedback or resistance:" If you look back the picture with the fan and compare it to this one, you'll notice an interesting coincidence - the same "symbol" is used in both cases to represent the action going on: thuirt mi ris gun a dhanamh - I told him not to do it dh'isd mi ruibh - I listened to you eughaidh mi ris - I will yell at him And then there is the remainder of expressions and idioms which use ri which are perhaps best just learned, things like ridh ri Dia 'at peace with God' where you could somehow invoke the above, but only with difficulty. Here's a list of usages which are difficult to predict but thankfully not that tricky to learn: ri + Verbal Noun &gt; to be V-PAST ri ithe - to be eaten ri rdh - to be said ri dhanamh - to be done aig + ri &gt; have to [present/non-tense] tha agam ri isteachd - I have to listen tha aca ri bruidhinn - they have to speak And then there is a number of verbs which take ri for reasons best known to themselves which you just have to learn such as feitheamh ri 'waiting for' and gabh ri 'to accept', but then every language has annoying constructions which don't fit into the pradigm easily.