SNICK'ER, SNIG'GER, verb intransitive [This can have no connection with sneer. the elements and the sense are different.] To laugh slily; or to laugh in one's sleeve. [It is a word in common use in New WNgland, not easily defined. It signifies to laugh with small audible catches of voice, as when persons attempt to suppress loud laughter.]
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI