Iavas
From Tolkien Gateway
Iavas was the Sindarin name for the season that corresponded to late summer and early autumn; 54 days between modern 12 August and 4 October.
Etymology
The word contains a possible Sindarin word for fruit plus the abstract ending -as.
The actual word for fruit is not known but it's most likely *iaf (cf. Q. yáve, yava)
Possible OS form *jabasse