This is the 7651st most frequent Japanese word.
包み隠さ
"Conceal" or "hide completely."
In this sentence, 包み隠さず (tsutsumi kakasu zu) is used as an adverb to indicate that the subject revealed everything straightforwardly, without hiding anything.
彼女は彼の秘密を包み隠さずに話した。
She spoke about his secret without concealing anything.
Here, 包み隠さず emphasizes the genuineness and transparency of the emotions depicted in the artist's work.
その画家は彼の感情を包み隠さずに絵に表した。
The artist expressed his emotions in his painting without concealing them.
包み隠さず is used to imply honesty and directness in responding to the inquiry.