Both Uses of

liaison
in
Ulysses, by James Joyce

He personally, being of a sceptical bias, believed and didn't make the smallest bones about saying so either that man or men in the plural were always hanging around on the waiting list about a lady, even supposing she was the best wife in the world and they got on fairly well together for the sake of argument, when, neglecting her duties, she chose to be tired of wedded life and was on for a little flutter in polite debauchery to press their attentions on her with improper intent, the upshot being that her affections centred on another, the cause of many liaisons between still attractive married women getting on for fair and forty and younger men, no doubt as several famous cases of feminin†
Chpt 16 *

personally, he would never be a party to any such thing), off the same bat as those love vendettas of the south, have her or swing for her, when the husband frequently, after some words passed between the two concerning her relations with the other lucky mortal (he having had the pair watched), inflicted fatal injuries on his adored one as a result of an alternative postnuptial liaison by plunging his knife into her, until it just struck him that Fitz, nicknamed Skin-the-Goat, merely drove the car for the actual perpetrators of the outrage and so was not, if he was reliably informed, actually party to the ambush which, in point of fact, was the plea some legal luminary saved his skin on.†
Chpt 16

Definitions:

(1) (liaison)
a person with the role of increasing communication and cooperation between two organizations; or an instance or other means of such communication
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Much more rarely (and found in classic literature such as the play Dangerous Liaisons), liaison can refer to a sexual meeting or affair -- especially one kept secret. Even more rarely, liaison can reference something used to thicken a sauce while cooking.