Thank-you for your question.
In American Sign Language a "loan sign" is either a finger-spelled
word or a sign that has been borrowed from another sign language. The
latter explanation is the one that is most commonly used today but
both are still in common usage as can be seen in these snippets.
"'Lexicalized' fingerspelled words used to be called 'loan signs'.
Some people still call lexicalized fingerspelled words 'loan signs'
but the term 'loan sign' more accurately applies to signs that were
'borrowed' from other signed languages and became part of ASL. [..]
In the old days many ASL instructors (including me) referred to
lexicalized fingerspelled words as 'loan signs'. Then, later we
stopped calling such signs (#EARLY, #BANK, #WHAT, #BACK, #BURN, etc)
loan signs and started calling them lexicalized fingerspelling. Now
we use the term 'loan signs' to describe signs like the new versions
of: JAPAN, CHINA, SPAIN, MEXICO, etc which were 'borrowed' from the
signed languages of those countries."
"Loan signs are signs that have been borrowed from other countries.
Quite a few loan signs consist of the signs that deaf people in other
countries use to refer to their country. For example, the loan sign
for Japan uses the index and thumb of each hand to trace a banana
shape in the air. This sign looks somewhat like the shape of Japan.
The old sign did a 'J' on the temple near the eyes in reference to the
shape of a Japanese person's eyes. The new sign shows more respect
for Japanese Deaf Culture."
"Lexical Borrowing - A process in which one language borrows a lexical
item from another language and incorporates it into its system. In
ASL, such a lexical item is generally referred to as a loan sign."
"Loan Signs are typically 3-5 letter words that are commonly
fingerspelled in ASL. You'll notice as you go through the lists below
that some of these fingerspelled words do have signs, however, many
times they are fingerspelled due to the letter's natural patterns and
ease of movement."
"LOAN SIGNS: Sometimes ASL borrows words from English and works them
into ASL vocabulary. This is not unique to ASL & English; many (if
not all) languages share some vocabulary when they come into contact
with one another. This process takes place in ASL by use of
lexicalized fingerspelling or what are commonly called LOAN SIGNS."
I hope this answers your question, should you require any further
assistance with this subject please do not hesitate to ask for