The observant reader will notice that this consonant ฃ (kho) is not the same as the consonant ข (kho) used at the start of the word for bottle ขวด (khuat). Generally, of course, the consonants are associated with a word which uses that letter (e.g. the consonant ก (ko) is found in the word ไก่ (kai) so we learn this consonant as ก ไก่ (ko kai)). Is this, therefore, a mistake we have here? I certainly thought so when I noticed it. The answer is no, it is not a mistake. The Thai letter ฃ (kho) is no longer used in written Thai. It is however still considered part of the Thai alphabet, and included when any Thai person learns the alphabet, and so that is why we include it on Lingopolo.
There is another consonant, ฅ (kho), which is also obsolete and exhibits the same phenomenon of the mnemonic word not using the same consonant as the one to which it is attached.