The SynSemClass event-type ontology evolved from the original idea to create a bilingual, later multilingual, synonym lexicon. This version (5.5.) builds on previous versions, but substantially enriches them with new synonymous classes (the number has risen from 1546 to 1993). In addition, version 5.5. has been extended by two items: Czech deverbal nouns (a small sample) and hierarchical relations. The hierarchical structure captures specialization and generalization relations between classes that are formally and technically unrelated in the original ontology, and it is now integrated with the main files constituting the lexicon (symsemclass55.zip). As a lexical-semantic resource, this version continues to link to similar resources, such as to PDT-Vallex, EngVallex, CzEngVallex, NomVallex, FrameNet, VerbNet, PropBank, Ontonotes Woxikon, E-VALBU, GUP, and German FrameNet), ADESSE, SenSem, AnCora, and Spanish WordNet and FrameNet. Examples of sentences in which multilingual synonyms have been used are also included (example_sentences.zip). Version with the original classes composition as automatically pre-suggested but later removed in the manual correction and further annotation process are included for completeness and historical reasons (removed_cms.zip). The individual languages are linked as follows (referenced resources not included but all are available online): The Spanish entries are linked to ADESSE (http://adesse.uvigo.es/), Spanish SenSem (https://grial-research.github.io/en/index.html), Spanish WordNet (https://adimen.ehu.eus/cgi-bin/wei/public/wei.consult.perl), AnCora (https://clic.ub.edu/corpus/en/ancoraverb_es), and Spanish FrameNet (http://sfn.spanishfn.org/SFNreports.php). The English entries are linked to EngVallex (http://hdl.handle.net/11858/00-097C-0000-0023-4337-2), CzEngVallex (http://hdl.handle.net/11234/1-1512), FrameNet (https://framenet.icsi.berkeley.edu/), VerbNet (https://uvi.colorado.edu/ and http://verbs.colorado.edu/verbnet/index.html), PropBank (http://propbank.github.io/), Ontonotes (http://clear.colorado.edu/compsem/index.php?page=lexicalresources&sub=ontonotes), and the Open English Wordnet (https://en-word.net/). The Czech verbal entries are linked to PDT-Vallex4.5 (http://hdl.handle.net/11234/1-5814), Vallex (http://hdl.handle.net/11234/1-4756), and  CzEngVallex (http://hdl.handle.net/11234/1-1512). The Czech deverbal nouns are linked to https://ufal.mff.cuni.cz/nomvallex/2.5. The German entries are linked to Woxikon (https://synonyme.woxikon.de), E-VALBU (https://grammis.ids-mannheim.de/verbvalenz), and GUP (https://github.com/UniversalDependencies/UD_German-GSD).