in these paragraphs, we have a clean knowledge base or ontology. But what if our ontology has to be queried, merged or linked with another one? Answer to this question is ontology alignment (a.k.a. ontology matching) and it has to be done in agreement to Big Data requirements (a recent and relevant review of schema alignment with structured data in Big Data era . A deep and recent review of ontology matching is presented in. Aspects of ontology matching which present an interest for us are mentioned there in terms of challenge. Some of those aspects like the use of external resources have a direct impact on ontology matching in the context of Big Data. It is the case of matcher selection, combination and tuning and user involvement. Challenge is relevant to us because matcher uses different techniques and to combine/tune them can improve results. Moreover, the improvements of these techniques can focus on specific aspects (volume, uncertainty) of ontologies. But these combinations can have a negative impact on processing time. The same remark can be done in the second “challenge” since the user can resolve matching errors but it is difficult to rely on users in large ontologies alignment.