"in pensive mood..."See in text(I Wandered Lonely as a Cloud)
The adjective “pensive” means dreamily thoughtful. A “pensive mood” can involve solemn thoughtfulness or musing. The speaker underscores the profound impact of his time among the daffodils by contrasting the rich natural imagery of the previous three stanzas with the starkness of lying on his couch in a melancholy, thoughtful state—which is transformed when he remembers the “jocund company” of the daffodils.
"jocund..."See in text(I Wandered Lonely as a Cloud)
The adjective “jocund” means cheerful, lively, and merry. Wordsworth continues to personify nature by attributing human characteristics—in this case, cheerfulness and the ability to provide company as people would—to the natural world.
In this context, the adjective “gay” means to be happy and excited. The speaker has transitioned from lonely wanderer to happy poet, who derives joy and inspiration from the natural scene around him.
"host..."See in text(I Wandered Lonely as a Cloud)
The noun “host” here refers to a sizable gathering and often appears in biblical contexts, such as a heavenly host. Wordsworth, who often romanticized nature in his work, perhaps suggests that the dancing daffodils are angelic or divine.
"vales..."See in text(I Wandered Lonely as a Cloud)
The noun “vale” is another word for valley. Wordsworth expands upon the experience of loneliness expressed in the first line by urging the reader to imagine a solitary cloud floating far above valleys and hills.